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Author of THE CARTOON HISTORY OF THE UNIVERSE 












ALSO By LARRy 60NI£fC 


THE CARTOON HISTORY OF THE UNIVERSE, VOLUMES 1-7 
THE CARTOON HISTORY OF THE UNIVERSE II, VOLUMES 6-13 
THE CARTOON HISTORY OF THE UNIVERSE HI, VOLUMES 14-19 
THE CARTOON HISTORY OF THE UNITE? STATES 
THE CARTOON 6UIPE TO THE COMPUTER 
THE CARTOON 6UIPE TO THE ENVIRONMENT (WITH ALICE OUTWATER) 
THE CARTOON 6UIPE TO GENETICS (WITH MARK WHEELIS) 

THE CARTOON 6UIPE TO (NON)COMMUN(CATION 
THE CARTOON 6UIPE TO PHYSICS (WITH ART HUFFMAN) 

THE CARTOON &UIPE TO SEX (WITH CHRISTINE PEVAULT) 

THE CARTOON 6UIPE TO STATISTICS (WITH WOOLLCOTT SMITH) 



TWt CRRTOON GUIDf TO 




LARRY GONICK 
& CRAIG CRIDDLE 



■ Collins 


An Imprint of HarperCollmsPublrshers 



THE CARTOON 6UfPE TO CHEMISTRY. Copyright @ 2005 by Lawrence &onick and Craig 
Criddle. All rights reserved. Printed in the United States of America- Mo part of this book 
may be used or reproduced in any manner whatsoever without written permission except 
in the case of brief quotations embodied in critical articles and reviews. For information 
address HarperCollins Publishers Inc., 10 East 53rd Street, New York, MY 10022. 

HarperCollins books may be purchased for educational, business, or sales promotional use. 
For information please write: Special Markets department, HarperCollins Publishers, Inc,, 
10 East 53rd Street, New York, NY 1 0022. 

FIR5T EPITIOM 

Library of Congress Cataloging-in-Publication data has been applied for. 

ISBN 0-06-093677 O 


01 09 09 ❖/RRP 10 9 9 



CONTENTS 

CHAPTER 1.1 

HIPPEN INGREPIENTS 

CHAPTER 2.17 

MATTER BECOMES ELECTRIC 

CHAPTER 3.45 

TOGETHERNESS 

CHAPTER 4. 67 

CHEMICAL REACTIONS 

CHAPTER 5 . 0S 

HEAT OF REACTION 

CHAPTER 6.105 

MATTER IN A STATE 

CHAPTER 7.129 

SOLUTIONS 

CHAPTER 0. 141 

REACTION RATE ANP EQUILIBRIUM 

CHAPTER 9. 165 

ACIP BASICS 

CHAPTER 10.191 

CHEMICAL THERMOPYNAMICS 

CHAPTER 11.209 

ELECTROCHEMISTRY 

CHAPTER 12.227 

ORGANIC CHEMISTRY 

APPENPIX.243 

USING LOGARITHMS 

INPEX.245 


















TO 


PEON CRIPPLE, 

WHO ALWAYS HAP TIME TO HELP 
HIS SON WITH SCIENCE FAIRS 

ANP 

THE MEMORY OF EMANUEL 60NICK ANP 
OTTO 60LPSCHMIP, CHEMISTS BOTH 


THE CARTOONIST WOULP LIKE TO THANK HIS ASSISTANT, HEMEN& 
“MOMO” ZHOU, WITHOUT WHOSE COMPUTER SKILLS, ARTISTIC ABILITY, 
ANP 600P HUMOR THIS BOOK WOULP HAVE TAKEN FOREVER- 



Chapter I 

Hidden Ingredients 


The very first cumuli reaction to impress our ancestors was FIRE. 


PERSONALLY, I WAS ■> 
FIRST STRUCK BY ™ 
17ECAYIN6 MEAT? Jg 





FIRE-AMP THOSE OTHER 
PROCESSES—REVEAL EP 
HIPPEM FEATURES 
OF MATTER. IF you 
HEAT A PIKE OF WOOP, 
ALL yOU 6 -ET IS A HOT 
PIE£E OF WOOP, AT 
FIRST... BUT SUPPEMLy, 
AT SOME POIMT, THE 
WOOP BURSTS INTO 
FLAME. WHERE PIP 
THAT £OME FROM? 



£HEMt$TRy is THE S£!EN£E THAT ANSWERS THAT QUESTION, ANP £HEMl£AL 
REACTIONS ARE THE STRAN6-E TRANSFORMATIONS THAT REVEAL MATTER’S 

HIPDEN PROPERTIED 


^HEMlSTRy IS A 
S£IEN£E ABOUT 
THE OKULT, THE 
HIPPEN, THE INVISI¬ 
BLE. NO WONPER 
IT TOOK SO LON£ 
FOR CHEMICAL SE¬ 
CRETS to com 
OUT... ANP IT ALL 
STARTEP WITH 

FIRE. 






PROBABLy THE BEST THIN6 ABOUT 
FIRE WAS THAT IT COULP BE USEP 
TO CONTROL OTHER CHEMICAL 
REACTIONS; COOKIN6-, FOR EXAMPLE! 


• r/5^ 



you KNOW HOW SCIENTISTS ARE'- IF THEY CAN COOK ONE THIN6, THEy’LL COOK 
ANOTHER. PRETTy SOON, THEy WERE COOKING ROCKS. 



SOUNPS CRAzy, BUT ONE OF THOSE 6REEN, CRUMBLy ROCKS MELTEP, CHAN&EP, 
ANP BECAME AN ORAN&E LIQUIP THAT COOLEP INTO SHINy, METALLIC COPPER. 



THIS ENCOURA&EP THEM 
TO SMELT REP ROCKS 
INTO IRON... BAKE MUP 
INTO BRICKS... SAUTE FAT 
ANP ASHES INTO SOAP- 
ANP (WITHOUT FIRE) TO 
CURPLE MILK INTO y06URT... 
FERMENT 6-RAIN INTO 
BEER... ANP CABBAGE INTO 
KIMCHEE. THE NEXT THIN6- 
yOU KNEW, CHEMISTRy HAP 

causep tfVIUZATtON/ 


3 









WHAT ACCOUNTS FOR MATTER'S SECRETS? THE ANCIENT GREEK'S CAME UP WITH 
AT LEAST THREE PlFFERENT THEORIES. 


THE ATOMISTS, LEP 

ev DEMOCRITUS, 

THOUGHT THAT MATTER 
WAS MAPE OUT OF TINy, 
JNPIVIS1BLE PARTICLES, 
OR ATOMS CA-TOM * 
“mo am. if you cut 

AMP CUT ANP CUT ANP 
CUT, THEy REASONEP, 

THE PROCESS HAP TO 
STOP SOMEWHERE. 


IF OBJECTS HAP INFlNITELy 
MANy PIECES, THEM EVERy- 
THIM6 WOULP TAKE FOREVER/ 


' IMSTEAP OF 
OMLy SEEMING 
THAT WAy... 





ANOTHER PHILOSOPHER, HERACLITUS, SU66ESTEP THAT EVER/THIN6 WAS 
MAPE OUT OF FIRE. 



BUT ATOMS COULPN’T BE 
SEEN, ANP... FIRE? I MEAN, 
REALLy/ THE CREAT ARI¬ 
STOTLE ANNOUNCEP THAT 
THERE WERE REALLy FOUR 
ELEMENTS, or basic 

SUBSTANCES, FROM WHICH 
ALL ELSE WAS COMPOSED 
THESE WERE AIR, EARTH, 
FIRE, anp WATER, other 

STUFF, HE OPINEP, WAS 
A BLENP OF THESE FOUR. 









OF THE THREE IPEAS, 

FOR SOME REASON, IT 
WAS ARISTOTLE’S THAT 
MOST INFLUENCEP MEPI- 
EVAL SCIENCE. IT WAS SO 
OPTIMISTIC IF EVERY¬ 
THING WAS A MIXTURE OF 
FOUR ELEMENTS, THEN YOU 
SHOULP BE ABLE TO TURN 
ANYTHING INTO ANYTHING 
ELSE JUST BY TWEAKING 
THE INGREPIENTS.I 






/>/ 

/ArJ 


THIS HOPELESS QUEST WAS TAKEN UP IN PERSIA BY JABIR (EIGHTH CENTURY} 
ANP AL-RAZ1 (TENTH CENTURY}, WHO INVENTEP ALL SORTS OF USEFUL LAB 
EQUIPMENT ANP PROCEPURES IN THE PROCESS. THIS PROVES YOU CAN MAKE 
TREMENPOUS PRACTICAL PROGRESS WITH STUPIP IPEAS. 


ANY GOLP YET? 


LET’S REPEFINE 
OUR GOALS... 






Ltll'l 


MEPIEVAL EUROPE BORROWEP THE ISLAMIC SCIENCE-ANP ITS NAME, AL£HEMV 
0“TH£ CHEMISTRY” IN ARABIC}—ANP ITS HUNGER FOR TRANSMUTEP GOLP. 
THE GERMAN ALCHEMIST M£NNI£ BRANP, FOR EXAMPLE, TRIEP TO MAKE 
GOLP BY PISTILLING bO BUCKETS OF URINE. 



S 





PESPITE THEIR WILPER SPECULATIONS, THE AL¬ 
CHEMISTS ACCOMPLISHEP a LOT in THE LAB'- THEy 
PERFECTEP PlSTILLATION, FILTRATION, TITRATION, 
ETC... THEy APVANCEP SLASSMAKINS, METAL- 
LUR^y, EXPLOSIVES, CORROSIVES... ANP THEy 
INVENTEP “FORTIFIEP WINE,” I.E., HARP LIQUOR... 



BUT THEIR LAB TECHNIQUE MISSEP ONE BIS THINS : THEY FAILEP TO COLLECT 
IF A REACTION CONSUMEP 6.AS, THE ALCHEMISTS HAP NO WAy OF 
KNOWINS. IF IT SAVE OFF SAS, THEy LET IT ESCAPE. 




THIS MEANT THEy COULP NEVER 
FULLy ACCOUNT FOR THE IN' 
6RED1ENTS OR PRODUCTS 
OF CHEMICAL REACTIONS. 


6 




THE MODERN STUDy OF &ASES OR “AIRS" BE 6 AN IN THE 1600 s, WITH SOME INVESTIGA¬ 
TIONS INTO THE EFFECTS OF AIR PRESSURE. CONSIDER THIS DEMONSTRATION gy OTTO 
VON GUERICKE (I602-I606). 


WHEN THE SPHERE ENCLOSED A NEAR 
VACUUM, HORSES COULDN’T PULL THE 
TWO HALVES APART/ 




AND THE TWO HEMI¬ 
SPHERES SEPARATED 
EASILy. 




EXPLANATION: AIR PRESSING ON THE 
OUTSIDE OF THE SPHERE PUSHES THE 
HALVES TOGETHER. ONLy WHEN THERE 
IS AIR INSIDE PRESSING OUTWARD 
WITH A BALANCING FORCE CAN THE 
HEMISPHERES BE EASILy SEPARATED. 


(%> 


HARD TO 
SEPARATE 


\ 

EASy TO 
SEPARATE 


AN EASy HOME EXPERI¬ 
MENT DEMONSTRATES 
THE SAME PRINCIPLE: 

FILL A BOTTLE WITH 
WATER AND CAP IT TIGHT- 
Ly. TURN THE BOTTLE 
UPSIDE DOWN AND 
IMMERSE THE CAPPED 
END IN A WATER BATH. 
(THE KITCHEN SINK WILL 
DO.) REMOVE THE CAP 
UNDER WATER. THE 
BOTTLE REMAINS FULL. 


AIR PRESSURE 
PUSHING ON 
THE SURFACE 
OF THE BATH 
HOLDS THE 
WATER UP IN 
THE BOTTLE. 


i # 1 1 1 


I U 4 












IS 


THIS UPSIPE-POWN BOTTLE 
BECAME A 6AS £OLLE£TOR 

! IN TME HANPS OF 

Joseph priestiey 

(mi-\eoA), A 
MINISTER WHO 
SET UP A LAB 
IN HIS 

^ KITCHEN. 


THE PRESSURE OF WZUMU- 
LATIN6 &AS PUSHES POWN 
THE COlVm OF LIQUIP. 


o o 



• ,*<•' t v 


PRIESTLE/S REACTIONS TOOK PLA£E IN A SEALEP 
FLASK £ONNE£TEP By A TUBE TO AN INVERTEP 
BOTTLE OF LIQUIP- THE BOTTLE WAS IMMERSEP 
IN THE SAME LIQUID THE REACTION &ENERATEP 
SAS THAT WOULP BUBBLE UP THROUGH THE 
LIOUIP ANP iOLLEOT IN THE BOTTLE. 



*WATER. UNLESS THE &AS WAS WATER SOLUBLE. IN VJWC\i 4ASE PRIESTLEY USE!? MERCURY. 


0 



FOR EXAMPLE, WHEN HE COMBINE? A 
STRONG ACIP WITH IRON FILING, THE 
REACTION PROPUCE? A 6AS, OR “INFLAM¬ 
MABLE AIR,” THAT BURNEP EXPLOSIVELY 
WE KNOW IT AS HYPR 06 EN. 


ANOTHER EXPERIMENT HEATEP A REP 
MINERAL CALLEP "CALX OF MERCURY” AS 
THE “CALX” MELTEP, PROPLETS OF PURE 
MERCURY CONPENSEP ON THE WALLS 
OF THE VESSEL, WHILE 6AS ACCUMU¬ 
LATE? IN THE WATER BOTTLE. 



9 










AT THE SAME 
TIME, IN FRANCE, 

ANTOINE 

LAVOISIER 

(17 4? - 1794; 
WAS POIN& A 
SIMILAR EXPERI¬ 
MENT, BUT IN 
REVERSE. 



LAVOISIER HEATEP A PIECE 
OF METALLIC TIN IN A 
TISHTLy SEALEP FLASK. 

A GRAYISH ASH APPEAREP 
ON THE SURFACE OF 
THE MELTING TIN. 
LAVOISIER HEATEP IT 
FOR A PAy ANP A 
HALF UNTIL NO 
MORE ASH 
FORMEP. 






HE NOTEP THAT THE WATER ROSE ONE~ 

FlFTW OF TME WAy into the flask. 



CONCLUSION; ONE-FIFTH OF THE AIR ORICHNALLV IN THE FLASK WAS REMOVEP By THE 
REACTION. THIS 6AS MUST HAVE COMBINEP WITH THE TIN TO FORM THE ASHy SUBSTANCE. 


AIR, SAIP LAVOISIER, 
MUST BE A MIXTURE 
OF TWO PIFFERENT 
l&ASES. ONE OF THEM, 
WHICH MAKES UP ONE- 
FlFTH OF THE TOTAL 
VOLUME, COMBINEP 
WITH THE TIN, WHILE 
THE OTHER PIP NOT, 



10 
















NEXT LAVOISIER REPEATED THE EXPERIMENT 
USIN6 MERCURY INSTEAP OF TIN. OVER 
HI6H HEAT, MERCURY ALSO FORMER AN ASH 
COR “CALX”; ANP REMOVEP 6AS FROM THE 
AIR. THEN, WHEN HEATER 6ENTLY, THE 
ASH 6AVE BACK THE 6AS ANP ALL THE 
ORIGINAL MERCURY, A LA PRIESTLEY. 



INTERPRETATION: THE ASH WAS A COM¬ 
POUND OF THE METAL ANP OXYGEN 
CA METALLIC OXlPE, WE WOULP SAY}. 



IN OTHER WORPS, PRIESTLEY’S “&OOP 
AIR" WAS THE SAME 6AS THAT LAVOI¬ 
SIER HAP FOUNP TO MAKE UP 20% OF 
THE ATMOSPHERE. THE FRENCH CHEMIST 
&AVE IT A NEW NAME: 0XV6EN- 


LAVOISIER CONFIRMEP THIS BY WEI&HIN&: 
THE WEIC-HT OF THE REMAINING CUNREAC- 
TEP; METAL PLUS THE WEIGHT OF ASH 
WAS GREATER THAN THE WEIGHT OF 
THE ORIGINAL METAL- 



LAVOISIER PREW A 
GENERAL CONCLUSION: 
COMBUSTION WAS A 
PROCESS WHEREBY 
FUEL COMBINEP WITH 
OXY&EN. IN OTHER 
WORPS, FIRE IS MOT 
AN ELEMENT; it s 

A CHEMICAL REACTION 
THAT GOBBLES UP 
0XY6EN ANP 6IVES 
OFF HEAT ANP LI6-HT. 



11 







AMP MORE; LAVOISIER 
ALSO FOUNP THAT THE 
TOTAL WEI6HT OF THE 
SEALEP FLASK PLUS 
CONTENTS WAS THE 
SAME BEFORE AMP 
AFTER THE REACTION. 



TIM OXlPE + 
UNREACTEP TIM + 
PE0XY6ENATEP AIR 


ANP SO HE LAJP POWk THE LAW OF 

«>N$ERVATION OF MATTER. 


In chemical reac¬ 
tions, nothing is 
created or de¬ 
stroyed. The ele¬ 
ments are merely 
rearranged in new 
combinations. 


LAVOISIER PROPOSEP A PROGRAM FOR 
CHEMISTRY: FlNP THE ELEMENTS, THEIR 
WEIGHTS, AMP THEIR RULES OF COMBI- 
NATION. THEN HE LOST HIS HEAP IN 
THE FRENCH REVOLUTION, ANP THE 
PROGRAM, LIKE HIS HEAP, HAP TO BE 
CARRIEP OUT BY OTHERS- 




CHEMISTS FOLLOWEP THROUGH WITH ENTHUSIASM, ANP BY 1 900 HAP PISCOVEREP 
ABOUT THIRTY ELEMENTS—ANP NONE OF THEM WAS WATER. IT TURNEP OUT TO 
BE A COMPOUNP OF HYPR06EN ANP OXYGEN. 



12 









AMP OWE MORE 

wAy vou’re 

WROW&... 


Sl6>H-.- 



AMP COMPOUND, TMEy FOUNP, WERE MO 
MERE ARISTOTELIAN MISH-MASH. INSTEAP, COM- 
POUNPS AUWAyS COMBI NEP ELEMENTS IM FIXEP 
PROPORTION*. WATER, FOR EXAMPLE, WAS 
ALWAyS MAPE OF EXACTLy TWO VOLUMES OF 
HyPR06EM 6AS AMP ONE VOLUME OF OXy&EM. 


AS A COOK, 
MATURE IS 
OBSESSIVE- 
COMPULSIVE' 






^>m 



SUCH PISCOVERIES 
LEP JOHN PALTON 
O7SC-1044; TO REVIVE 

the ATOMIC THEORy 
Of MATTER. EACH 
ELEMEMT, HE REASOMEP, 
WAS MAPE OF TJMy, INPI- 
VISIBLE ATOMS. THE ATOMS 
OF AMy OME ELEMEMT 
ARE ALL ALIKE, BUT 
PIFFER FROM THE ATOMS 
OF OTHER ELEMENTS. 



13 





MEANWHILE, THEy KEPT UP THE HUNT FOR NEW ELEMENTS, FINPIN& NEARLy 
SEVENTY BY THE 1060s— ANP WHAT A LIST IT WAS/ ELEMENTS MISHT BE 
SOLIP, LIQUIP, OR GASEOUS; YELLOW, SREEN, BLA6K, WHITE, OR COLORLESS; 
CRUMBLY OR BENPY*, WILPLY REAfTTIVE OR RELATIVELY INERT. 



ONE THIN6 SOON 
BECAME 4LEAR: SOME 
ELEMENTS WERE MORE 
ALIKE THAN OTHERS. 
SOWUM ANP POTAS¬ 
SIUM BOTH REA^TEP 
VIOLENTLY WITH 

water. CHLORINE, 
FLUORINE, anp 
BROMINE all £OM- 
BINEP ON A ONE-TO- 
ONE BASIS WITH 
SOPIUM ANP POTASSIUM. 
CARBON anp SILICON 
BOTH HOOKEP UP WITH 
two OXY6ENS... gtc. 


14 





ONE MORNIN6 IN 1069, A RUSSIAN 

namep PM1TRI MENPELEGV 

0034-1907,) WOKE UP WITM AN IPEA; 
LIST THE ELEMENTS IN ORPER OF 
INCREASING ATOMIC WEIGHT ANP PO A 
“TEXT WRAP” AT REGULAR INTERVALS. 


HAVENT 
you EVER 
HAP THAT 
PREAM? 




THE RESULT WAS A SORT OF TABLE, WITH THE ELEMENTS ARRANGEP IN ROWS. 
HERE’S A BABY VERSION OF MENPELEEV’S TABLE. (YOU’LL SEE THE REAL THING 
NEXT CHAPTER.; 


HYPR06EN 


LITHIUM 

BERYLLIUM 

BORON 

CARBON 

SOPIUM 

MAGNESIUM 

ALUMINUM 

SILICON 

POTASSIUM 

CALCIUM 




THE ELEMENTS 
SHOWEP A PGRlOPI£ 
PATTERN: EACH 
VERTICAL COLUMN 
CONTAINEP CHEMI¬ 
CALLY SIMILAR ELE¬ 
MENTS. IN FACT, 
MENPELEEV NOTEP 
GAPS FARTHER POWN 
THE TABLE ANP SUC¬ 
CESSFULLY PREPICTEP 
NEW ELEMENTS 
THAT WOULP FILL 
THEM/ 


FINE. NOW 
WHERE’S MY 
TEPPY BEAR? 




IS 





THE TABLE WAS GREAT, BUT 
HOW TO EXPLAIN IT? IN 
FACT, HOW TO EXPLAIN 
ANY OF CHEMISTRy? WHAT 
ACCOUNTS? FOR ATOMIC 
WEIGHTS, OR WHICH ELE¬ 
MENTS COMBINE? WITH 
WHICH? CHEMISTS HA? COME 
FAR IN INTERPRETING 
THEIR OBSERVATIONS, BUT 
A QUESTION STILL HUNG 
IN THE AIR ; WHy? ^ 


i/V\ 


LOVE THAT 
QUESTION! 




Ijdo 


TO FIN? THE ANSWER, SCIENTISTS FOLLOWE? THE 
SAME LINE OF THOUGHT THEY ? BEEN USING ALL 
ALONG: IF SUBSTANCES ARE MAPE OF ELEMENTS, 



16 



Chapter 2 

Matter Becomes Electric 


NATURE HAP ANOTHER SECRET 
BESIDES FIRE- AT LEAST, IT. 
LOOKED LIKE ANOTHER ^ 
SECRET AT FIRST... 


r IVE SOT A 
MILLION OF ’EM. 


THIS ONE INVOLVED AMBER- OR AS THE GREEKS CALLED IT, ELEKTRA. 


f you MEAN 
THE MOMMY- 
MURPERING 
MINX WAS 
REALLy NAMED 

v AMBER? > 


ir 



WHEN THEY RUBBED THIS STUFF WITH 
FUR, IT ACTED STRANGELY, ATTRACTING 
FLUFF AND FEATHERS AND THE HAIR ON 
THE BACK OF YOUR ARM. 


FORSOOTH, WHAT¬ 
EVER THAT MEANS/ 


CENTURIES LATER, AN ENGLISHMAN NAMED WILLIAM 
GILBERT FOUND OTHER MATERIALS WITH THE SAME 
PROPERTY. HE SAID THEY ALL HAD “ELEKTRA.” 



THEN PEOPLE NOTICED THAT THERE WERE REALLY TWO KINDS OF “ELECTRIC” 
MATERIALS; ONE REPELLED WHAT THE OTHER ATTRACTED, AND VICE VERSA. 



17 





AROUNP 1750 

BENJAMIN 
FRANKLIN 

ivob-mo) 
first callep 

THESE TWO 
KINPS OF 
ELECTRICITY 

POSITIVE anp 
NEGATIVE. 



POSITIVE, SAIP FRANKLIN, REPELS POSITIVE-, 


NEGATIVE REPELS NEGATIVE; ANP POSITIVE 


ANP NEGATIVE ATTRACT EACH OTHER ANP 


CANCEL EACH OTHER OUT. IN ORPINARY, 


NEUTRAL MATTER, OPPOSITE CHARGES 


ARE PRESENT IN EQUAL AMOUNT. 



i 


NEGATIVE CHARGES CAN SOMETIMES FLOW 
OUT OF A SUBSTANCE, CREATING A CHARGE 
IMBALANCE— AN EXCESS OF NEGATIVITY 
HERE ANP POSITIVITY THERE- 


•+■ 4?"— 4 

T + - 1 + 
+ “ '* , 

_ -L - ^ ■ 

I ■+- - 


BUT BECAUSE OF THE MUTUAL ATTRACTION, 
THE NEGATIVES MAY SUPPENLY FLOW BACK 
TO THE POSITIVE CHARGE WITH A SPARK. 



sr 






“TWO NIGHTS AGO, BEING ABOUT 
TO KILL A TURKEY BY THE SHOCK 
FROM TWO LARGE GLASS JARS,* 
CONTAINING AS MUCH ELECTRICAL 
FIRE AS FORTY COMMON PHIALS, I 
INAPVERTENTLY TOOK THE WHOLE 
THROUGH MY OWN ARMS ANP BOPY, 
BY RECEIVING THE FIRE FROM THE 
UNITEP TOP WIRES WITH ONE HANP 
WHILE THE OTHER HELP A CHAIN 
CONNECTEP WITH THE OUTSiPE OF 
BOTH JARS.” 

-BENJAMIN FRANKLIN, 1750 


ANP NOW FOR 
SOMETHING 
REALLY BIG-' 




*JUST OWE OF THE WAYS THE FUN-LOVIN6 FOUNPIW& FATHER LIKEP TO AMUSE HIMSELF! 


19 










WITH THE INVENTION OF THE ELECTRIC 
BATTER/ CW VOLTA IN \WO), ONE COULP RUN 
A STEAPY STREAM OF NEGATIVE CHARGE— 
A CURRENT —THROUGH A COPPER WIRE, ANP 
MAYBE THROUGH OTHER MATERIALS AS WELL. 


CHEMISTS TRIER RUNNING ELECTRICITY 
THROUGH ORPINARY WATER. TWO METAL 
STRIPS, OR ELECTROPES, WERE CONNECTER 
TO A BATTERY ANP IMMERSEP IN WATER. 



AS CHARGE BUILT UP ON THE ELECTROPES, 
BUBBLES OF HYPR06EN 6AS APPEAREP 
AT THE NEGATIVE STRIP, OR CATHOPE 
BUBBLES OF OXYGEN FORMER AT THE 
POSITIVE STRIP, OR ANOPE. 







ELECTRICITY SPLITS 
WATER' SCIENTISTS 
SOON TRIER THIS 

ELECTROLYSIS 

(ELECTRIC SPLIT¬ 
TING ON OTHER 
SUBSTANCES. MELTEP 
TABLE SALT, THEY 
FOUNP, YIELPS 
METALLIC SOPiUM 
AT THE CATHOPE 
ANP &REEN, TOXIC 
CHLORINE 6AS 
AT THE ANOPE. 



IT’S A BI6 LEAP FROM FINPIN6 
ELECTRICITY IN A FEW PLACES 
TO SEEING IT EVERYWHERE, BUT 
THATS SCIENCE FOR YOU/ 


LON6 LIVE THE 
INPUCTIVE METHOP' 






LvM^T 






!\ pf; CUL6 1 \ I \ N ^ 


pm?* 




BY THE ENP OF THE 19TH CENTURY, 
SCIENTISTS WERE CONVINCEP THAT 
ATOMS WERE MAPE OF ELECTRIC 
IN&REPIENTS. 


19 








ANP SO THEY ARE. HERE’S TNE IPEA - - 


ATOMS ARE MAPE UP OF SMALLER, ELEC¬ 
TRICALLY CHARGEP PARTICLES (ANP. SOME 
NEUTRAL PARTICLES TOO}. EACH ATOM HAS 
AN EQUAL NUMBER OF POSITIVE ANP NEGA¬ 
TIVE CHARGES- THE NEGATIVELY CHARGEP 
PARTICLES, CALLEP ELECTRONS, WEIGH 
LITTLE ANP MOVE AROUNP EASILY. 



OTHER KINPS OF ATOMS ACQUIRE ELECTRONS 
TO BECOME NEGATIVELY CHARGEP IONS, 
OR ANIONS, ATTRACTEP TO ANOPES. 



A PEPARTING ELECTRON LEAVES BEHINP A 
POSITIVELY CHARGEP ATOM, OR POSITIVE 
ION. SUCH IONS, ATTRACTEP TO CATHOPES 
(WHICH ARE NEGATIVE}, ARE CALLEP 
CATIONS (PRONOUNCEP “CAT-EYE-ONr;. 



IN TABLE SALT, FOR EXAMPLE, SOPIUM 
CATIONS ARE ATTRACTEP TO CHLORIPE 
ANIONS ANP ARRANGE THEMSELVES INTO 
A CRYSTAL, SOPIUM CHLORIPE- 



PURING ELECTROLYSIS, THESE IONS 
MIGRATE TOWARP THE ELECTROPES, 
ANP THE SALT PISSOCIATES. 


All-Important 



ATOMS COMBINE CHEMI¬ 
CALLY BY SHARING OR 
TRANSFERRING ELECTRONS. 






Fact: 


SO—TO UNPERSTANP CHEMISTRY, WE NEEP 
TO SEE HOW ELECTRONS BEHAVE WITHIN 
EACH ATOM. 


THAT’S THE ^ 
BIG PICTURE!^ 





HOW SMALL IS THE SMALL PICTURE? LETS TRY SHRINKING POWN ONE MILLION TIMES. 
A HUMAN HAIR IS NOW THIRTY STORIES THICK- BACTERIA ARE THE SIZE OF TORPEPOES... 
ANP ATOMS ARE JUST BARELY VISIBLE AS TINY SPECKS. 





SHRINKING ANOTHER THOUSANP TIMES BRIN&S US TO NANOMETER IP' 9 METER) 
SCALE. I’M JUST SHy OF 2 run TALL. THE ATOMS ARE NOW ABOUT ONE-TENTH MY 
SIZE. WE’RE IN A VERY ENERGETIC ENVIRONMENT LI6HT WAVES ARE ZOOMIN6- 
AROUNP, ANP ALL THE ATOMS ARE JI66LIN&. 

this is GRAPHITE 

FROM SOME PENCIL 
SHAVINGS. THE CARBON 
ATOMS ARE ARRANGE? 

IN SHEETS THAT CAN 
SLiPE OVER EACH OTHER 
EASILY. THIS EXPLAINS 
WHY &RAPHITE IS A 
600P LUBRICANT.* 



LET'S SHRINK TEN MORE TIMES TO ATOMIC SIZE-10" 1O METER-ANP LOOK AT A 
SIMPLE CARBON ATOM. I CAN VAGUELY SENSE SOME ELECTRONS HUMMING 
AROUNP, ALTHOUGH THEY’RE AWFULLY HARP TO PIN POWN. 



*IN PURE FORM. PEN^Il LEAP J* A MIXTURE OF 6RAPHJTE ANP £LAy. 


21 






NOW I’M A HUNPREP TIMES SMALLER, AT Pl£OMET6R ^ALE- THAT’S A 
MILLIONTH OF A MILLIONTH, OR 1 0' n ACTUAL SIZE. THERE AT LAST ARE 
THE POSITIVE £HAR6ES, ALL LUMPEP TOGETHER AT THE VERy CENTER OF 
THE ATOM IN A TINy £ORE OR NUCLEUS. IF THE PIAMETER OF THE ATOM 
WERE THE LEN6TH OF A FOOTBALL FIELP, THEN THE NUCLEUS WOULP BE 
SMALLER THAN A PEA- THE ATOM IS MOSTLy EMPTy SPA^Ef 






ORPINARILY, THE PARSON 

nucleus consists of twelve 
particles; six protons 
WITH A POSITIVE CHARGE ANP 
SIX NEUTRONS WITH NO 
CHARGE AT ALL. THE PROTOWS’ 
CHARGE IS BALANCEP BY 
THE SIX HOVERING NEGA¬ 
TIVE ELECTRONS, SO THE 
ATOM IS NEUTRAL OVERALL. 



THE NUCLEUS IS HELP TOGETHER BY A POWERFUL, SHORT-RANGE ATTRACTION 
CALLEP THE 6TRON6 FORGE/ WHICH OVERCOMES ELECTRICAL REPULSION. 
THIS INTENSE PULL MAKES MOST NUCLEI VIRTUALLY INPESTRUCTIBLE. THIS VERY 
SAME CARBON ATOM HAS BEEN ROAMING THE EARTH FOR BILLIONS OF YEARS. 



NEARLY ALL THE ATOM’S MASS 
IS CONCENTRATEP IN THE TINY 
NUCLEUS. EACH PROTON ANP 
NEUTRON (THEY HAVE ALMOST 
EXACTLY THE SAME WEIGHT) 

HAS 1940 TIMES THE MASS OF 
AN ELECTRON. 


‘SCIENTISTS PON’T INVENT NEARLY SUCH COLORFUL NAMES AS THEY USEP TO. 



ZA 









NOW FOR A FEW HELPFUL 

definitions: 

AN ELEMENT’* ATOMIC NUMBER 
I* THE NUMBER OF PROTON* IN 
IT* NUCLEU*. CARBON’* ATOMIC 
NUMBER I* 6. 


K 



ALMO*T 99% OF ALL CARBON ATOM* ON EARTH HAVE *IX NEUTRON* ALON& 
WITH THEIR *IX PROTON*. WE CALL THI* CARBON-12 (ANP *OMETIME* WRITE H), 
*INCE IT* MA** I* *0 CLO*E TO THAT OF TWELVE NUCLEAR PARTICLE*. 


MORE PRECI*ELY, CHEMI*T* PEFINE 
an ATOMIC MA$$ UNIT, OR 
AMU, to be preci*ely ONE- 
TWELFTH THE MA*$ OF A 
n C ATOM. THE COMMON 
CARBON ATOM HA* A MA** OF 
EXACTLY 12 .OOOOOO AMU, BY 
PEFINITION. ALL OTHER ATOMIC 
MA**E* ARE COM PUTEP RELATIVE 
TO THI* REFERENCE. 



THE OTHER 1.1 % OF CARBON ATOM* HAVE *EVEN NEUTRON*. THERE MU*T *TILL 
BE *IX PROTON* (OTHERWI*E IT* NOT CARBON/;, BUT THI* £ARBON-13 ATOM 
WEI6H* APPRECIABLY MORE THAN CARBON-12. 


n C, H, ANP A VERY RARE 
FORM, 14 C, WITH EIC-HT 
NEUTRON*, ARE CALLEP 
l$OTOPE5 OF CARBON. 
THE f*OTOPE* OF AN 
ELEMENT HAVE THE *AME 
NUMBER OF PROTON*, BUT 
PIFFERENT NUMBER* OF 
NEUTRON*. 


H NUCLEU* 


Gmm 

H C NUCLEU* 




V? 





THE AMPLEST ATOM OF ALU IS HVPR06EN, SYMBOL H, WITH AW ATOMIC 
WUMBER OF OWE. IW NEARLY ALL HYPROGEN ATOMS, A SINGLE ELECTRON ORBITS 
A SINGLE PROTOW, BUT ISOTOPES WITH OWE ANP TWO NEUTRONS ALSO EXIST. 



2 H fPEUTERlUAO 


? H (“TRITIUM") 


ANOTHER FAMILIAR ELEMENT IS OXy&EN, SYMBOL 0. ITS ATOMIC NUMBER IS 
0. ITS MOST COMMON ISOTOPE HAS EIGHT NEUTRONS FOR AN ATOMIC 
WEIGHT OF APPROXIMATELY 16.* OTHER ISOTOPES INCLUPE 17 0 AN? 18 0. 


|gj 






r how ^ 
graphically 

BORING. 



NOW YOU MIGHT ASK, IF EVERY 
ELEMENT HAS AN ATOMIC NUMBER, 
POES EVERY NUMBER HAVE AN 
ELEMENT? IS THERE AN ELEMENT 
WITH 37 PROTONS? S2? 92? 

ft 


m ACTUAL MA55 OF % A 15.9949 AMU. THE "MINING MA55" 15 CONVERTED TO THE ENER6Y OF THE 
5TR0WG FORCE THAT BIMPG THE NUCLEU5 TOGETHER. OTHER ATOM* HAVE SIMILAR FRACTIONAL WEIGHTS. 



26 


NATURE, IT TURNS OUT, MAKES ATOMS WITH EVERY NUMBER FROM 1 (HYPRO&EN; 
TO 92 (URANIUM}, ALTHOUGH A FEW ELEMENTS IN THERE ARE VERy SCARCE. 


THE SEQUENCE STOPS 
THERE BECAUSE LAR6-E 
NUCLEI (THOSE ABOVE 09, 
BISMUTH) ARE UNSTABLE. 
BEyONP URANIUM, 92, THEy 
FALL APART SO QUICKLY 
THAT WE PONT SEE THEM 
IN NATURE. PHySICISTS CAN 
MAKE NUCLEI WITH MORE 
THAN 92 PROTONS, BUT 
THEy PONT SURVIVE LON6. 


HERE IS A LIST OF THE 92 NATURALLY OCCURRING ELEMENTS'- 


1. Hydrogen M 

29. Copper, Cu 

57. Lanthanum, La 

2. Helium, He 

30. Zinc, Zn 

50-71—Never mind these? 

3. Lithium, U 

31. Gallium, &a 

72. Hafnium, Hf 

4. Beryllium, Be 

32. Germanium, &e 

73. Tantalum, Ta 

5. Boron, B 

33. Arsenic, As 

74. Tungsten, W 

b. Carbon, C 

34. Selenium, Se 

75. Rhenium, Re 

7. Nitrogen, N 

35. Bromine, 0r 

7b. Osmium, Os 

8. Oxygen, 0 

3 b. Krypton, Kr 

77. Iridium, Ir 

9. Fluorine, F 

37. Rubidium, Rb 

70. Platinum, Pt 

10. Neon, Ne 

30. Strontium, Sr 

79. Cold, Au 

11. Sodium, Na 

39. yttrium, y 

90. Mercury, Hg 

12, Magnesium, Mg 

40. Zirconium, Zr 

01. Thallium, Tl 

13. Aluminum, A! 

41. Niobium, Nb 

02. Lead, Pb 

14. Silicon, Si 

42. Molybdenum, Mo 

03. Bismuth, Bi 

15. Phosphorus, P 

43. Technetium, Tc 

04. Polonium, Po 

1b. Sulfur, S 

44. Ruthenium, Ru 

05. Astatine, At 

17. Chlorine, Cl 

45. Rhodium, Rh 

9b. Radon, Rn 

10. Argon, Ar 

4b. Palladium, Pd 

07. Francium, Fr 

19. Potassium, K 

47. Silver, Ag 

00. Radium, Ra 

20. Calcium, Ca 

40. Cadmium, Cd 

09. Actinium, Ac 

21. Scandium, Sc 

49. Indium, In 

90. Thorium, Th 

22. Titanium, Ti 

50. Tin, Sn 

91. Protactinium, Pa 

23. Vanadium, V 

51. Antimony, Sb 

92. Uranium, U 

24. Chromium, Cr 

52. Tellurium, Te 

(93, 94, ANP ABOVE ARE 

25. Manganese, Mn 

53. Iodine, 1 

ARTIFICIAL ANP UNSTABLE.) 

2b. Iron, Fe 

54. Xenon, Xe 


27. Cobalt, Co 

55. Cesium, Cs 


20. Nickel, Ni 

5b. Barium, Ba 




27 




The Elusive Electron 

TO TURN THAT RATHER STARK LIST INTO A PERIOD TABLE—FOR THAT IS OUR 
£OAL—WE NOW TURN TO THE ATOM’S OTHER MAIN IN&REPIENT, ITS ELECTRONS. 
THESE, WE SHOULD WARN YOU, PEFY COMMON SENSE, BECAUSE ELECTRONS, YOU SEE, 
OBEY THE BIZARRE RULES OF MOPERN PHYSICS CALLEP QUANTUM ME£HANI£$. 


WRAP yOUR MINP 
AROUNP THIS-- AN ELEC¬ 
TRON is A PARTICLE, 
LIKE A MARBLE, BUT 
ALSO A WAVE, LIKE A 
BEAM OF LI6HT. AS A 
PARTICLE, IT HAS A PE- 
FINITE MA$$» CHARGE, 
ANP SPIN, BUT IT ALSO 
HAS A WAVELENGTH. 
IT’S “SMEAREP OUT” IN 
SOME WAy. ITS PRECISE 
POSITION IS ALWAyS A 
BIT UNCERTAIN. MAKE 
SENSE? WE PIPNT 
THINK SOI 



IN ITS 6UISE AS A PARTICLE, AN ELECTRON INHABITS A SORT OF “PROBABILITY 
CLOUP"-NOT A CIRCULAR ORBIT. THE PENSEST PARTS OF THE CLOUP ARE WHERE 
THE ELECTRON IS LIKELIEST TO U BE"-IF IT CAN BE SAIP TO BE ANYWHERE, 

WHICH IT CAN’T EXACTLY. THESE CLOUPS NEEP NOT BE ROUNP, BY THE WAY. 



RE6ION 
OF HIGHEST 
PROBABILITY OF 
FINPIN6 AN 
ELECTRON 



NUCLEUS 


20 





WE CAN ALSO VISUALIZE THE ELECTRON AS A WAVE, BEAMING AROUNP THE NUCLEUS. 
IN THIS PICTURE, QUANTUM MECHANICS TELLS US THAT THE ELECTRON IS ALWAyS A 
“STAN PI NS WAVE.” THAT IS, IT “SOES AROUNP" THE NUCLEUS A WHOLE NUMBER 
OF WAVELENGTHS 1, 2, 3, 4, ETC., BUT NEVER A FRACTIONAL VALUE. 



IN OTHER WORPS, ONLy CERTAIN PISCRETE “ORBITS" ARE AVAILABLE TO AN ELECTRON IN 
AN ATOM. 


LET’S CONTRAST THIS WITH A MORE FAMI- IMAGINE THAT SOMETHING OlVES 
LIAR SySTEM: A PLANET ORBIT) NS A STAR. THE PLANET A NUPSE, APPJNS 
___ ENERSy TO IT. 



THE EKTRA ENERSY PUSHES THE PLANET IN FACT, WITH A BIS ENOUSH JOLT, THE 

INTO AN ORBIT FARTHER FROM THE STAR- PLANET WILL ESCAPE THE STAR’S SRAVI- 

TATIONAL PULL COMPLETELY 


W£W WINNER- 



29 





AN ORBITING ELECTRON IS SIMILAR: IT MAY 

BUT THE ELECTRON MUST JUMP TO AN 

ABSORB A JOLT OF ENERGY, TOO, IN THE 

ORBIT CONSISTENT WITH A WHOLE 

FORM OF A BEAM OF LIGHT, FOR EXAMPLE. 

NUMBER OF WAVELENGTHS. 

< 



THIS MEANS IT CAN ABSORB ONLY CERTAIN FIXED AMOUNTS OF ENERGY: JUST 
ENOUGH TO JUMP THE ELECTRON TO ONE OF THE HIGHER AVAILABLE ORBITS. UNLIKE 
A PLANET, WHICH Cm ABSORB ENERGY GRAPUALLY ANP ORBIT AT ANY PlSTANCE, AN 
ELECTRON’S ENERGY IS LIMITEP TO CERTAIN VALUES. 



WE SAY THE ELECTRON’S ENERGY IS 
QUANTIZED: IN ANY GIVEN ATOM, THE 
ELECTRONS CAN ASSUME ONLY CERTAIN 
FlXEP, PISCRETE ENERGY LEVELS. 



THE ELECTRON CONFIGURATIONS WITHIN 
EACH ENERGY LEVEL ARE CALLEP ORBI¬ 
TALS (NAMEP, NO POUBT, BY NOSTALGIC 
PHYSICISTS PREAMING OF PLANETS;. 



10 







- ‘ 1 ' 


waf| 

&MM& 




tne-jiWty.-'W! ? 
! CJrftS 




THE SIMPLEST EXAMPLE IS HYDROGEN: 
OKIE ELECTRON PULLEP BY A SINGLE 
PROTON. THE ELECTRON CAN INHABIT 
ANy ONE OF SEVEN AFFERENT LEVELS, 
OR “SHELLS,” MI5LEAPIN&LY PEPICTEP 
HERE AS CIRCULAR ORBITS. 


TO REMOVE THE ELECTRON COMPLETELY 
ANP MAKE A HYPRO&EN ION REQUIRES 
13.6 eV. THIS IS CALLEP THE ATOM'S 

IONIZATION ENER&y. 


TO RAISE AN ELECTRON FROM SHELL t 
TO SHELL 2 REQUIRES AN ENER6Y EQUAL 
TO THE PI FFERENCE (-3A)- (-13.6) * 
13.6-3.A * 10.2 eV. 


THIS 6RAPH SHOWS THE ELECTRON’S ENERGY IN EACH SHELL. 


THE ENERGY UNIT HERE IS 
THE ELECTRON VOLT 
(<N). ONE eV IS THE ENERGY 
6AINEP BY ONE ELECTRON 
PUSHEP BY ONE VOLT. 
(NOTE: IN ATOMS, AN ELEC¬ 
TRON’S ENERGY IS NEGATIVE, 
SINCE ENERGY MUST BE 
APPEP TO PULL THE ELEC¬ 
TRON FREE OF THE NUCLEUS. 
THE FREE STATE IS TAKEN 
TO HAVE ENERGY = O.) 


0 12 3 4 5 6 7 







MOW LET'S 
( BUILP SOME 
I BIGGER ATOMS' 



LARGER ATOMS, LIKE HELIUM, LITHIUM, OR TIN, 
ALSO HAVE UP TO SEVEN ELECTRON SHELLS. BUT 
IN THESE ATOMS, THE “HIGHER” SHELLS CAN HOLP 
MORE ELECTRONS THAN LOWER SHELLS CAN. 


HIGHER-SHELL ELECTRONS CAN ALSO HAVE MORE 
COMPLEX CONFIGURATIONS, OR ORBITALS, THAN 
LOWER-SHELL ELECTRONS. yOU CAN THINK OF 
THESE ORBITALS AS ENERGY SUBLEVELS. DIFFERENT 
SUBLEVELS ARE CALLED $, p, d, ANP f, ANP EACH 
ORBITAL CAN HOLP UP TO TWO ELECTRONS. 



SHELL 1 HAS ONLY AN s ORBITAL, 
WHICH IS SPHERICAL. IT CAN HOLP 
ONE OR TWO ELECTRONS. 



SHELL 2 HAS ONE 5 ANP THREE p ORBITALS, 
WHICH LOOK SOMETHING LIKE PUMBBELLS. WHEN 
FULL, THIS SHELL HOLPS EIGHT ELECTRONS. 



SHELL 3 HAS ONE 5, THREE p, ANP 
FIVE d ORBITALS CFORGET PRAWING 
THEM ALLO. WHEN FULL, IT HOLPS 
10 ELECTRONS (t X [1 + 3 + 5] )■ 



ANP THREE MORE d ORBITALS 


SHELLS 4 ANP HIGHER HAVE ALL OF 
THAT PLUS SEVEN f ORBITALS-UP TO 
32 ELECTRONS TOTAL- 




5 OF THESE 7 OF THESE 





THIS PIA6RAM SHOWS THE 
ENER&y LEVELS OF THE 
PlFFERENT ORBITALS. THE 
FARTHER UP THE PA£E, THE 
HIGHER THE ENER^y. 

MOTE THAT THE SHELLS 
HAVE OVERLAPPING 
ENERGIES E.6., SOME 
ORBITALS IM SHELL 4 
(Ad AMP 4f; HAVE HIGHER 
EMER^y THAN SOME ORBITALS 
IM SHELL 5 (5s), EVEM 
TH0U6H 4 IS “LOWER” THAN 5. 

MOTE: 2s MEANS THE s 
ORBITAL IM SHELL 2, 4d 
MEANS THE d ORBITAL IM 
SHELL 4, ETC. EAdH ARROW 
LEAPS TO THE ORBITAL 
WITH THE NEXT-HI&HEST 
ENER^y. 

AS WE BUILP UP AN ATOM, 
EAdH ELECTRON “WANTS” TO 
GO INTO THE LOWEST 
AVAILABLE ENERGY STATE. 

WE START AT THE LOWEST, 
THEN WHEN THAT FILLS UP, 
GO TO THE NEXT-LOWEST, 
ETC. 


s& 

£* 

U> 

2 

Lil 


NOTE. EAdH dIRdLE REPRE- K 
SENTS A SIMPLE ORBITAL, ^ 
I.E., AN ELEdTRON PAIR. 


9f_ 

ooooooo 







MOW LET'* BUlLP *OME ATOM*. 


1. HYPRO&EN, H, HA* OME ELECTRON. 
IT MU*T BE IN THE LOWE*T *HELL’* 
s ORBITAL. WE WRITE THI* A* Is 1 . 


2. HELIUM, We, APP* A *ECONP ELECTRON 
TO THI* 5 ORBITAL. NOW *HELL 1 I* FULL, 
ANP WE WRITE Is 2 . 



Is 2 



REMEMBER; TWO 
ELECTRON* PER 
ORBITAL, TOP*/ 


?. LITHIUM, U, HA* TO PUT THE THIRP 4. BERYLLIUM, Be, COMPLETE* THE 2s 
ELECTRON IN A NEW *HELL, *HELL 2. ORBITAL, 


ts^s 1 



INNER 

*HELL 



FROM HERE 
ON, WE OMIT 
THE INNER 
*HELL IN THE 
PRAWIN&. 


*. BORON, B, APP* AN 
ELECTRON TO A 2p 
ORBITAL 



1s 2 2s 2 2p 1 


b. CARBON, C, APP* AN 
ELECTRON TO THE *ECONP 
p ORBITAL. 



7. NITROGEN, M, APP* AN 
ELECTRON TO THE THIRP 



1s 2 2s 2 2p 3 


0. 0XY6EN, 0 



9. FLUORINE, F 



1s 2 2s 2 2p 5 


IP. NEON, Me, COMPLETE* 
*HELL 2. 



1s 2 2s 2 2p^’ 



TO FINP OUT WHAT HAPPENS IN ELEMENT #11, LOOK AT THE CHART ON p BB. AFTER 
2p FILLS UP, THE LOWEST-ENER6Y AVAILABLE ORBITAL IS Bs, IN THE THIRP SHELL, 
FOLLOWEP BY Bp. SO WE HAVE: 

11. SOPlUM, No. WE CAN WRITE THIS AS 12. MA&NESIUM, Mg. SIMILARLy, WE CAN 
NeBs 1 , INPICATIN6 ONE s ELECTRON OR- WRITE THIS AS NeBs 2 . 

BITIN6- OUTSIPE A £ROUP OF ELECTRONS 
JUST LIKE NEON’S. 



IB. ALUMINUM, At 14. SILICON, Si 15. PHOSPHORUS, P 



16. SULFUR, S 17. CHLORINE, C\ 19- AR60N, Ar 



NeBs 2 3p 4 NeBs 2 Bp 5 NeBs 2 Bp 6 


IF you COMPARE THESE ATOMS WITH THOSE ON THE PREVIOUS PA6E, yOU WILL SEE 
THAT ELEMENTS 11 -10 ARE LIKE “016 SISTERS" TO ELEMENTS 3-10. EACH OF THE 
ATOMS ON THIS PA6E HAS AN OUTER SHELL IDENTICAL TO THAT OF THE ATOM 
JUST EI6HT ELEMENTS BEHINP IT/ 


BS 



WE WRITE THE FIRST EIGHTEEN ELEMENTS IN A TABLE. IN ANY COLUMN, ALL THE ATOMS 
HAVE THE SAME OUTER ELECTRON CONFIGURATION. 



- 

m- 

#r;-£ !%p 



a: 

* a"> . .Aw. ■•• sa V.X> 1 


: ;,r . 

£■= T.;i 

-a * • 


. V :Lc.. X 

Be 

" % ^"4 ••;«**::: • 

. ; A .>«cv. 

.»•••>»•• >V 

fp-iv ••• 

.r , «T* , ' : :.. 



Ne 

:?*.*“* . 2 ! L* 

X- 


jr<-. 

a* * • 

P 

•• • ’1 W/wv^ X 

• |^*::*<* 

i7L~j 
, ...*,. .. 



CEXCEPT HELIUM, WHICH 
GOES IN THE LAST 
COLUMN BECAUSE ITS 
OUTER SHELL IS FULLU 


NEXT, ACCORDING TO THE CHART ON P. 33 THE 4s ORBITAL FILLS AS WE BEGIN THE FOURTH 
ROW OF THE TABLE NEXT, SAyS THE CHART, ELECTRONS BEGIN TO OCCUPY THE 3d 
ORBITALS. BEFORE WE CAN CONTINUE IN THE FOURTH SHELL, TEN ELECTRONS MUST 
GO INTO THESE INNER ORBITALS. WE WRITE THESE TEN ELEMENTS ON A LOOP, SINCE 
WE'RE STALLED FILLING THE FOURTH SHELL. 



AFTER THOSE TEN, WE CAN RESUME PUTTING ELECTRONS IN THE FOURTH SHELL, UNTIL 
ALL THE 4s ANP 4p ORBITALS ARE FULL AT ELEMENT 36, KRYPTON, Kr. 









AGAIN, WITHIN 
EACH COLUMN 
THAT LIES “FLAT 
ON THE PAGE,” 
ATOMS HAVE 
OUTER SHELLS 
THAT LOOK 
THE SAME. 
















THE FIFTH ROW FILLS UP IN EXAiTLy THE SAME WAV AS THE FOURTH: FIRST THE 
OUTER 5, THEN THE INNER d, THEN THE OUTER p. 



THE ELEMENTS THAT ARE 
"FLAT ON THE PASE” ARE 
aLLEP /AAIN-6ROUP 
ELEMENTS. THOSE in 
THE LOOPS ARE £ALLEP 
TRANSITION METALS. 


THE SIXTH ROW HAS A LOOP WITHIN A LOOP, AS 4f ORBITALS FILL BEFORE Si (SEE 
P. 33.9 AS THERE ARE SEVEN <4f ORBITALS, THIS LOOP HAS 14 ELEMENTS. IT IS £ALLEP 

THE LANTHANIDE SERIES, AFTER ITS first element, lanthanum. 


1 jj 


■'£Z-Z~ 

r:-Ur 




'm 

Hi 

EH 

-r»*K 




14 

ttS 


55 p 

. 

s 

17^ 

M^Ar: 

fic. 


■@§ 

ss 

1 

jg-Tii 


y> 

Br 

Xr 

V 

1 

Si 

1 

1 

gS 

•: Te 


r X* 

|P® 

r jgg 

&r; : 

r??i'Ru 

i 


0? 

. Bi 

■44- 

05 

r'j'Ut >:■ 





77 i 






E*i 


ilg^l 









THE SEVENTH ROW PETERS OUT WHEN WE RUN 
OUT OF ELEMENTS. 


ANP THAT IS 
THE ENP OF 
OUR TABLE! 

















TURK! THIS PA6E SIPEWAYS TO SEE THE PERIOPId TABLE AS IT IS USUALLY PISPLAYEP. 
THE d-LOOPS ARE FLATTENEP OUT TO SHOW EVERY ELEMENT. THE 14-ELEMENT f-LOOP, 
AFTER 97, LANTHANUM, IS CUT OUT ANP PUT BELOW THE MAIN TABLE. THE TABLE’S 
“TAIL," THE AdTINIPE SERIES AFTER 99, IS ALSO AT THE BOTTOM. 



FOR A WONPERFULLY INFORMATION-RIdH PERIOPId TABLE WITH A PETAILEP PROFILE OF 
EVER/ ELEMENT, SEE htip://f>earlltar\L 9 ov/perio<ltc/default*htm, ANOTHER WEB-BASEP 
TABLE, AT wwwxolorado.edu/physics/2000/applets/a3.htTnl , SHOWS THE EWER6JES OF ALL 
THE ELECTRONS IM EVERy ATOM* * 


30 



WHAT’S SO PERIOPIC ABOUT THE PERIOPIC TABLE? WHAT 
PROPERTIES REPEAT THEMSELVES IN THE COLUMNS? WHAT 
TRENPS PO WE TRACE ALON6 THE ROWS? 

The Outermost Electrons 


MOVING LEFT TO RI6HT 
ALON6 A ROW OF MAIN- 
6ROUP ELEMENTS, THE 
NUMBER OF OUTER ELEC¬ 
TRONS 60ES UP STEAPILy. 
6-ROUP 1 ELEMENTS ALL 
HAVE ONE OUTER ELECTRON, 
6R0UP 2 ELEMENTS HAVE 
TWO, ETC., UNTIL THE LAST 
6-ROUP, WHICH ALL HAVE 
EI6HT. TRANSITION METALS 
HAVE EITHER ONE OR TWO 
OUTER ELECTRONS.* 


NUMBER Of OUTER-SHELL ELECTRONS 


1 2 ? A <7 b 7 0 



THE OUTER ELECTRONS, CALLEP VAL£NC£ ELECTRONS, ACCOUNT FOR MOST 
CHEMICAL REACTIONS. 


Atomic Size 

601N6 AL0N6 A ROW FROM 
LEFT TO RI6HT, ATOMS 6ET 
SMALLER, ANP M0VIN6 POWN 
A COLUMN, THE/ 6ET BI66ER. 

REASON; M0VIN6 TO THE 
RI6HT, THE BI66ER CHAR6E 
OF THE NUCLEUS PULLS 
ELECTRONS CLOSER IN. 

60! N6 POWN A COLUMN, 

THE OUTER ELECTRONS ARE 
IN HI6HER SHELLS, HENCE 
FARTHER AWAY FROM THE 
NUCLEUS. 


A* 




V _____ 

TRANSITION METALS' INNER ELECTRONS SOMETIMES HAVE H16-H ENOU6H ENER&y TO ACT LIKE OUTER 
ELECTRONS, HOWEVER. 









Ionization Energy 


an ATOM’S IONIZATION ENQtey- 
THE ENER6-Y NEEPEP TO REMOVE AN 
OUTER ELECTRON—PEPENPS ON THE 
ATOM’S SIZE. 

FOR EXAMPLE, £ROUP 1 ELEMENTS 
HAVE A SINGLE VALENCE ELECTRON 
FAR AWAY FROM THE NUCLEUS. IT 
SHOULP BE EASy TO PRy OFF. THESE 
ELEMENTS SHOULP HAVE LOW IONI¬ 
ZATION ENERGIES. 



MOVING RI6HTWARP ALON& A ROW, 
ELECTRONS ARE CLOSER TO THE 
NUCLEUS, WHICH HOLPS THEM MORE 
Tl&HTLY, SO IONIZATION ENERGIES 
SHOULP RISE TO A MAXIMUM IN THE 
LAST COLUMN. 



ANP SO THEy PO. 6ROUP 1 ELEMENTS— 
LITHIUM, SOPIUM, POTASSIUM, RUBJPIUM, 

anp cesium, the ALKALI METAL6- 

SHEP ELECTRONS EASILY. 


AT THE START OF THE NEXT ROW, WITH 
A NEW OUTER SHELL, IONIZATION ENERGY 
PROPS A£AIN. THIS SRAPH SHOWS THE 
PERIOPICITY OF IONIZATION ENERGY- 



IN FACT, THEY ARE SO REACTIVE 
THAT THEY ARE NEVER FOUNP NATUR¬ 
ALLY PURE, BUT ALWAYS IN COMBI¬ 
NATION WITH OTHER ELEMENTS. 




ATOMIC NUMBER 



Electron Affinity 

THIS PROPERTY, TME FLIP SI PE OF IONIZATION 
ENERGY, MEASURES AN ATOM'S “WILLINGNESS” 
TO BECOME AN ANION, I.E., TO APP AN EXTRA 
ELECTRON. 

STRAY ELECTRONS MAY FEEL THE NUCLEAR 
PULL ANP ATTACH THEMSELVES TO ATOMS, 
ESPECIALLY IF AN UNFILLEP OUTER ORBITAL 
IS AVAILABLE. 


COME HEEERE, LITTLE J* 


ELECTRON! 


my" / 

^ * 


<£> - 


HIGHER ELECTRON AFFINITy 






THE NEXT-TO-LAST 
GROUP IS ESPECIALLY 
ELECTRON HUNGRY. THESE 
ELEMENTS, THE HALO¬ 
GENS, HAVE A SMALL 
PIAMETER ANP ONE 
VACANT SPOT IN A p 
ORBITAL. AS YOU MIGHT 
IMAGINE, HALOGENS 
COMBINE WITH THE 
ELECTRON-SHEPPING 
ALKALI METALS OF 
GROUP 1. TABLE SALT, 
Na£ l, IS A PRIME 
EXAMPLE OF AN ALKALI - 
HALOGEN COMPOUNP. 


ATOMS TOWARP THE RIGHT SIPE 
OF THE PERIOPIC TABLE TENP TO 
HAVE HIGHER ELECTRON AFFINI¬ 
TY: SMALL PIAMETER (SO ELEC¬ 
TRONS CAN GET CLOSERS BIG 
PULL FROM THE NUCLEUS, ANP 
AN UNFILLEP ORBITAL OR TWO. 




EXCEPT IN > 
THE LAST GROUP' 
THEY’RE FULL.' 




THAT WAS MY ELECTRON, 
BUT I PONT MINP... 








41 





THE PERIOPIC TABLE 15 BROAPLY PIVIPEP AL0N6 A STAIRSTEP BORPER INTO 
METALS AMP NONMETALS, WITH A FEW CONFUSEP “METALLOIP5" STRAPPLINS 
THE FENCE- METALS, ON THE LEFT, VASTLY OUTNUMBER NONMETALS, THANKS 
TO ALL THE ELEMENTS IN THE “LOOPS”. 



METALS TENP TO SlVE UP ELECTRONS FREELY, WHEREAS NONMETALS GENERALLY 
PREFER TO SAIN OR SHARE ELECTRONS. BUT METALS PO SHARE ELECTRONS 
AMONS THEMSELVES, FORMINS TISHTLY-PACKEP, PENSE SOUPS. NONMETALS 
USUALLY HAVE A LESS COHESIVE STRUCTURE. 


Properties of metals Properties of nonmetals 


HISH PENSITY 

HISH MELTINS POINT ANP BOILINS 
POINT 

SOOP ELECTRICAL CONPUCTIVITY 
SHINY 


OFTEN LIOUIP OR SASEOUS AT ROOM 
TEMPERATURE 

BRITTLE WHEN SOUP 

PULL-LOOKINS 

POOR ELECTRICAL CONPUCTIVITY 


MALLEABLE (EASY TO SHAPED 
PUCTILE (EASY TO STRETCH INTO 

wires; 

REACTIVE WITH NONMETALS 



AZ 





















ALL EXCEPT 
HELIUM MAVE 
EI6HT OUTER 
ELECTRON*. 


TME LA*T COLUMN OF THE 
PERIODIC TABLE I* UNIOUELy 
*TRAN*E. IT* PEN1ZEN*. BECAU*E 
THEy LIVE FAR TO THE RI6-HT, 
HAVE mU IONIZATION 
ENERGIES, *0 THEy PON’T 
EA*ILy MAKE CATION*. THEy 
AL*0 HAVE LOW ELECTRON 
AFFINITY BECAU*E THEIR OUTER 
ORBITAL* ARE FULL, *0 THEy 
PON’T MAKE ANION* EITHER.' 


THEy JU*T- 
*IT THERE. 



mm 


IN FACT, THEy RARELy 
REACT WITH ANyTHIN*. 
THEY JU*T FLOAT 
AROUNP IN AN UNCON¬ 
NECTED *TANPOFFl*H, 
*A*EOU* *TATE ANP 
*0 ARE KNOWN A* 

NOBLE you 

ALREAPy KNOW ABOUT 
NEON, BUT THE MO*T 
COMMON I* ARGON 
(ALMO*T 1 % OF THE 
ATMO*PHERE). IT I* U*EP 
IN ORPINARy INCANPE*- 
CENT LI6-HT BULB*, 
*INCE IT WON'T REACT 
WITH THE HOT 
FILAMENT. 


I NEEP NOTHING 
I yiELP NOTHIN*. 





43 



JUST LIKE REAL MOBILITY, THE 
NOBLE SASES ARE THE EMVY OF 
THE COMMON ELEMENTS. EVERY¬ 
ONE WANTS THAT FULL COMPLE¬ 
MENT OF EISHT OUTER ELECTRONS. 


YOU’RE SO 
STABLE/ 


f YOU’RE 
BENEATH 
MY 

NOTICE... 




WE CALL THIS THE RULE OF EI6HT: AN ATOM TEN US TO PICK UP OR SIVE 
AWAY JUST ENOUGH ELECTRONS TO MAKE EISHT IN ITS OUTER SHELL—AN 

electron octet. ^ ^ 


METALS TENI? 
TO SHE? 
ELECTRONS- 





NONMETALS 
TEN? TO AC¬ 
QUIRE THEM. 



ANP THIS BRINGS US TO THE 
SUBJECT OF OUR NEXT CHAPTER. 


00/ IS THIS WHERE 
THEY SET EXPOSE? TO 
WEIR? RAYS AN? TURN 

into RADIOACTIVE 
WEREWOLVES? 


UM... NOT 
EXACTLY- 


m 


i 



BEFORE SOI NS ON, PLEASE TAKE A MOMENT TO APPRECIATE HOW AMAZINS 
THIS CHAPTER HAS BEEN. STARTINS FROM SOME WEIRP PROPERTIES OF 
ELEMENTARY ATOMIC PARTICLES, SCIENCE HAS MANASEP TO PESCRIBE THE 
ATOM, EXPLAIN THE PERIOPIC TABLE, ANP ACCOUNT FOR MANY CHEMICAL 
PROPERTIES OF THE ELEMENTS. NO WONPER ATOMIC THEORY HAS BEEN 
CALLEP “THE SIN6LE MOST IMPORTANT IDEA IN SCIENCE.” 


44 



Chapter 3 

Togetherness 


IF ELEMENTS AN!? ATOMS 
WERE ALL THERE WERE, 
CHEMISTRY WOULP BE A 
PRETTY PULL SUBJECT. 
ATOMS WOULP JUST 
JI66LE AROUNP BY THEM¬ 
SELVES LIKE A BUN£H 
OF NOBLE 6ASES, ANP 
NOTHING WOULP HAPPEN. 




BUT IN REALITY, CHEMISTRY 15 A SORT OF FRENZY OF TOGETHERNESS. MOST 
ATOMS ARE GREGARIOUS LITTLE FRITTERS... ANP THAT’S HOW WE’RE GOING TO 
PRAW THEM, SOMETIMES... AS LITTLE CRITTERS. 



THE COMBINATIONS ARE ENPLE5S. METALS BONP TO METALS, NONMETALS TO 
NONMETALS, METALS TO NONMETALS. SOMETIMES ATOMS CLUMP TOGETHER IN 
LITTLE CLUSTERS ANP SOMETIMES IN IMMENSE CRYSTAL ARRAYS. NO WONPER 
THE SUBJECT IS SO- SEXY.' 




ATOMS COMBINE WITH EACH OTHER BY EXCHAN6IN& 
OR SHARING ELECTRONS- THE PETAILS PEPENP ON 
THE PREFERENCES OF THE PARTICULAR ATOMS 
INVOLVEP. POES AM ATOM “WANT TO SHEP AM 
ELECTRON OR TO PICK ONE UP? ANP HOW BAPLY? 



ELECTRONS/ WHO )/ UM... V 
, NEEPS ’EM? r y( ER... AH... 




METALS, AS WE’VE SEEN, TENP 
TO 6-IVE UP ELECTRONS, THOUGH 
SOME METALS PO SO MORE EW- 
THUSIASTICALLy THAN OTHERS. 

A CHEMIST WOULP SAy THAT 
METALS ARE MORE OR LESS 
ELECTROPOSITIVE. 


WHATEVER. 




NONMETALS ARE MORE OR LESS 
ELECTRONEGATIVE: THEy tenp 
TO ACCEPT EXTRA ELECTRONS. SOME 
NONMETALS, LIKE FLUORINE ANP 
OXySEN, AVIPLy &RAB ELECTRONS, 
WHILE OTHERS, SUCH AS CARBON, 
CAN TAKE THEM OR LEAVE THEM. 


IN BETWEEN ARE THE METALLOIPS, WHICH ARE COMPLETELY AMBIVALENT. 


' WUf&s 

/CA 




SI6-H 


47 






Ionic Bonds 

WHEN A HIGHLy ELECTROPOSITIVE ATOM Ml GETS 
A HIGHLy ELECTRONEGATIVE ONE, THE RESULT 
IS AN IONIC BONP. THE ELECTROPOSITIVE ATOM 
EASILy GIVES AWAy ONE OR MORE ELECTRONS 
ANP BECOMES A POSITIVELT CHARGEP CATION. 
THE ELECTRONEGATIVE ATOM LOVES TO ACQUIRE 
EXTRA ELECTRONS ANP IN POING SO BECOMES 
AN ANION. 




THEIR MUTUAL ATTRACTION PACK'S THEM TOGETHER IN A 
PENSE, REGULAR \OH\C CRY5TM' IN THE CASE OF 
SOPIUM ANP CHLORIPE,* EACH ION HAS A SINGLE CHARGE 
SO NEUTRALITy IS ACHIEVEP By THIS SIMPLE CUBIC 
ARRANGEMENT _ 




ygi HM... PIP THIS 
CM GET OUT OF 
HANP OR / 
' ' JEH WHAT? 


■ — 


yss... i 

CAN’T 
MOVE.^ 



IF yOU LOOK CLOSELy 
AT TABLE SALT, yOU CAN 
SEE THAT THE CRySTALS 
ARE LITTLE CUBES-EACH 
ONE A MONSTER ARRAy 
OF SOPIUM ANP 
CHLORIPE IONS- 


“SINGLE-ATOM ANIONS ARE NAMEP By 
APPING “IPE" TO THE ROOT OF THEIR 
ELEMENTAL NAME; FLUORIPE, OXIPE, ETC. 



48 





OTHER IONS MAy FORM AF¬ 
FERENT CRySTALLINE STRUCTURES. 
WHEW CALCIUM, WHICH GIVES UP 
TWO ELECTRONS, COMBINES WITH 

chlorine, which accepts owiy 
OWE, two chloripe ions are 

WEEPEP TO NEUTRALIZE EACH 
CALCIUM. WE WRITE AN IOW 
WITH IT* ELEMENT SyMBOL ANP 
CHARGE. *0 THE CALCIUM IOW I* 
Ca 1+ , ANP CHLORIPE I* C\~. 



THE FORMULA OF THESE IONIC CRySTALS I* GIVEN “IN LOWEST TERMS." EVEN 
THOUGH A SOPIUM CHLORIPE CRySTAL MAy CONTAIN TRILLIONS OF ATOMS, WE 
WRITE ITS EMPIRICAL FORMULA AS Had THIS SHOWS THAT THE CRySTAL 
HAS ONE SOPIUM ION FOR EACH CH LORI PE. IN THE SAME WAy, CALCIUM 


CHLORIPE IS WRITTEN CaCL. 



OCCASIONALLY IONI- 
CALLy BON PEP ATOMS 
HAVE NO NATURAL 
CRySTALLINE ARRANGE¬ 
MENT. INSTEAP THEY 
CLUMP TOGETHER INTO 
SMALL GROUPS CALLEP 
MOLECULES. boron 
TRIFLUORIPE, BF ? , IS 
AN IONIC iOMPOUNP 
THAT IS GASEOUS AT 
ROOM TEMPERATURE. 



49 





SOME JONS CONSIST OF 
MORE THAN ONE ATOM. 
WE’LL SEE HOW TO BUILP 
THESE POLYATOMIC 
10 NS LATER IN THE CHAP¬ 
TER. THESE THIN6-S BE¬ 
HAVE VERY MUCH LIKE 
MONOATOMIC IONS, EX¬ 
CEPT FOR THEIR SHAPE. 
THE WHOLE STRUCTURE 
ACTS AS A SIN&LE 
CHAR6EP UNIT. 


COME TO 
PA-PAI 


it 



'QoP 


A - 


A TypjCAL EXAMPLE IS 5UUFATE, *0/', AN ANION THAT BONPS WITH Ea 2+ 
TO MAKE CALCWM SULFATE, £aS0 4 , AN IN&REPIENT OF WALLBOARP. 



EACH POLYATOMIC ION MUST BE 
RE&ARPEP AS A SINGLE ION. FOR 
EXAMPLE, ALUMINUM HYPROXIPE, 
WHICH COMBINES Al* + ANP OW, 
MUST HAVE THREE HYPROXIPES 
TO BALANCE EACH ALUMINUM. THE 
FORMULA IS WRITTEN Al(OH) y 
ANP THE CRYSTAL STRUCTURE 
LOOKS LIKE THIS-. 







IONIC BONDS ARE STRONG 
IT TAKES A LOT OF 
EMER&y TO BREAK THEM. 
THIS EXPLAINS WHY MOST 
IONIC CRYSTALS HAVE 
SUCH HI6-H MELTIN6 
POINTS^ TREMENDOUS 
HEAT IS NEEDED TO JAR 
THE IONS LOOSE AND 
6-ET THEM SLOSHING 
AROUND AS A LIQUID. 



AND YET-HIT A SALT CRYSTAL WITH 
A HAMMER AND IT CRUMBLES. WHY 
SHOULD IT BE SO BRITTLE? 



ANSWER: WHEN WHACKED, THE CRYSTAL 
MAY DEVELOP TINY CRACKS, AND ONE 
LAYER MAY SHIFT SLIGHTLY ACROSS 
ANOTHER. 



-t-h " -H + 

-+-+-+-+■ 
h -e — y- —^ ~ 


THIS SHIFT CAN ALI6N POSITIVES 
OPPOSITE POSITIVES AND NEGATIVES 
OPPOSITE NEGATIVES. NOW THE TWO 
CHUNKS REPEL EMM OTHER, AND THE 
CRYSTAL LITERALLY FLIES APART. 




BUT NOT ALL 
(CRYSTALS 
BEHAVE THIS 


WAY-METALLIC 
CRYSTALS, FOR 
EXAMPLE- 



51 








Metallic Bonds 


PURE METALS ALSO FORM CRYSTALS, THOUGH YOU PROBABLY PON’T THINK OF 
THEM THAT WAY- THEY LACK THE TRANSPARENCY AN 17 SPARKLE OF NaCt ANP 
OTHER IONIC CRYSTALS, ANP THEY USUALLY ARENT BRITTLE. 



WHEN MANY METALLIC ATOMS 
GET TOGETHER, THEY SHEP AN 
ENTIRE "ELECTRON SEA” THAT 
ENGULFS THE METAL IONS. 



PULLEP FROM ALL PIRECTJONS, THE METAL IONS FINP IT HARP TO MOVE, ANP 
THEY PACK TIGHTLY WETHER IN CRYSTALLINE STRUCTURES. THERE ARE SEVERAL 
POSSIBLE PACKING ARRANGEMENTS, ALL OF THEM PENSE. HERE ARE TWO. 



BOPY-CENTEREP CUBIC; EACH ATOM FACE-CENTEREP CUBIC; EACH ATOM 

SURROUNPEP BY EI&HT OTHERS SURROUNPEP BY TWELVE OTHERS 











METALS TEMP TO BE 
GOOP CONPUCTORS 
OF ELECTRICITy. TME 
LIGHT, FREE ELEC¬ 
TRONS MOVE AROUNP 
EASILY NEGATIVE 
CHARGE COMING 
FROM OUTSIPE CAN 
PUSH THE “SEA” OF 
ELECTRONS, MAKING 
A CURRENT. 





rO 




LIKE ANy CRySTAU BEING WHACKEP 
By A HAMMER MAy CAUSE A METAL’S 
CRySTALLINE STRUCTURE TO CRACK 
ANP SHIFT. 


BUT UNLIKE IONIC CRySTALS, THE METAL’S 
IONIC REPULSION IS OVERCOME By THAT 
NEGATIVE SEA OF ELECTRONS HOLP1NG 
ALL THE ATOMS IN PLACE- 


©CD fr 


<±) <±> ® 

<& © © 


®©0©<D 




WHO P HAVE 
THOUGHT 
ELECTRONS 
WOULP HAVE 
A CALMING 
EFFECT? 


o & 0 


® o <s 




SO, INSTEAP OF SHATTERING, A 
METAL TENPS TO BENP OR STRETCH.* 

/'TtsukeA 




SB 







Covalent Bonding and 
Molecules 


i mr 
CM T BE 
K7THERCP. 


OMME 6WIMEJ 





METALLIC BONPING HAPPENS WHEN 
A LOT OF ELECTROPOSITIVE ATOMS 
ARE TRAPPEP BY ALL THE ELEC¬ 
TRONS THEy SHARE. IT’S LINE A 
COMMUNAL HOUSEHOLP. 




IONIC BONPS FORM WHEN A HIGHLY ELECTRO¬ 
NEGATIVE ATOM MEETS A HIGHLY ELECTRO¬ 
POSITIVE ONE. ELECTRONS ARE HANPEP OFF, 
ANP ONE ATOM GETS SOLE CUSTOPy. 



ANP THEN THERE’S EVERYTHING 
ELSE; THE BONPS BETWEEN TWO 
ELECTRONEGATIVE ATOMS- 


GIMME 


GIMME 







HERE... 
NO- UM... 


W 


X 

/* 



OR BETWEEN ATOMS THAT ARE 
ONLY SOMEWHAT ELECTRONEGATIVE 
OR ELECTROPOSITIVE. ONE SHEPS 
ELECTRONS, BUT RELUCTANTLY- 
THE OTHER ACCEPTS THEM, BUT 
HALF-HEARTEPLY- ANP THE RESULT 
IS A SORT OF MARRIAGE, OR JOINT 
CUSTOPY ARRANGEMENT. 


S4 







UNPAIREP 
ELECTRON- 
. BAP! , 


(A 



THE SIMPLEST POSSIBLE EXAM¬ 
PLE IS HyPRO&EN. A LONE 
HyPRO&EN ATOM HAS AN UN- 
PAIREP ELECTRON, WHICH THE 
ATOM CAN EITHER 6IVE UP OR 
PAIR WITH ANOTHER ELECTRON. 


B WHEN ONE 

HyPRO^EN ENCOUN¬ 
TERS ANOTHER, 
THEIR ELECTRONS 

NATURALLy PAIR UP IN A SINGLE, SHAREP 
ORBITAL. 



THIS PAIR PULLS ON BOTH NUCLEI, SO IT HOLPS THE ATOMS TOGETHER. THE 
BONP IS CALLEP 60VALEMT, BECAUSE BOTH ATOMS CONTRIBUTE EQUALLY 


EACH HyPRObEN ATOM 
“THINKS” IT HAS A FULL 
Is VALENCE SHELL, SO 
THE RESULTING TWO¬ 
SOME, OR HyPROfi-EN 

MOLECULE, H 2 , is 

STABLE. 



f AT NORMAL 
TEMPERATURES, 
HyPR06EN 6AS 
IS ALWAyS IN 
. MOLECULAR 




MORE EXAMPLE* 
OXyGEN, THE *ECONP- 
MO*T ELECTRONEGA¬ 
TIVE ELEMENT RAFTER 

fluorine;, ha* *ix 

VALENCE ELECTRON*. 
WE INDICATE THI* 
WITH A “LEWI* 
PIAGRAM" THAT 
REPRE*ENT* EACH OF 
THE*£ OUTER 
ELECTRON* A* A POT. 


• • 

O 


AGH! I *MELL 
, RU*T! 




// 


WHEN TWO OXyGEN* GET TOGETHER, THET BONP COVALENTLy W *HARING 
FOUR ELECTRON*, A* *HOWN IN THI* LEWI* PIAGRAM: 


0=0 


NITROGEN, WITH FIVE VALENCE ELECTRON*, 
FORM* TRIPLE COVALENT BONP* TO MAKE 
N 2 OR N=*N. 

:N:::Ns 

MANy OTHER NON-METAL*, INCLUPING THE 
HALOGEN*, FORM PIATOMIC ('TWO-ATOM ; 
MOLECULE* IN THI* WAT 

• • •• •• •• 

:F:F: sClsCl: 


HERE, TOO, BOTH ATOM* NOW 
HAVE A FULL OUTER OCTET. 
(COUNT THE ELECTRON*/; 
WHEN FOUR ELECTRON* ARE 
*HAREP IN THI* WAy, WE CALL 
IT A POUBMs POMP ANP 
*OMETIME* WRITE IT A* 0=0. 


THE ATMO*PHERE 
I* MO*TLy N 2 
ANP 0 2 . y 


_) 


• t #• 



COVALENT BONPIN* INVOLVED ELECTRON 
*HARIN* BETWEEN A SPECIFIC PAIR OF 
ATOM*. IT’* LIKE A HANP5HAKE. 



*JNCE ATOM* HAVE ONLy A LlMlTEP NUM¬ 
BER OF “HANP*," COVALENT COMPOUND* 
ARE U*UALLy FOUNP IN THE FORM OF 
fbOlQCV LE$, OR *MALL, PI*CR£TE 
&ROUP* OF ATOM*. 



GVERy MOLECULE IN 
A PURE *UB*TANCE 
HA* THE *AM£ 
COMPO*ITION. WE 
WRITE IT* FORMULA 
ACC0RPIN6 TO THE 
NUMBER OF EACH 
KINP OF ATOM 
PRE*ENT. 


H U 

X)' 

H,0, WATER 


H 


0^ 

f 


C 6 U n 0 6 , (, LUCO*E 
^ CBLOOP *U6ARy 


Q “-0 


u 


\ ,0 

0 

/ « 




9 

o' \ 

o s * 


MH,, AMMONIA 

H s rt 

I 

H 


OCCA*IONALLy WE PO *EE COVALENTLy BONPEP CRy*TAL*. PIAMONP, FOR 
EXAMPLE, CON*l*T* OF A *0-CALLEP £0VAIENT NETWORK OF CARBON 
ATOM*. _ 








Molecular Shapes 


50 FAR, WE’VE LOOKEP ONLY AT COVALENT BOW PS BETWEEN TWO IPENTICAL ATOMS. 
NOW LET’S SEE MOW DIFFERENT ATOMS CAN SMARE ELECTRONS.__ 


TARPON PIOXIPE, FAMOUS EXHAUST GAS, C0 2 '. 
CARBON HAS FOUR VALENCE ELECTRONS ANP 
OXYGEN MAS SIX, SO WE WRITE'- 

‘C* anu :6* 

THESE CAN COMBINE LIKE SO: 

Owe WO 

•« t* ^ 

ANP CO, HAS TWO POUBLE BONPS. 


r iOUNT ELECTRONS 
TO MAKE SURE THEY'RE 
ALL THERE, ANP THAT 
. EVERY ATOM HAS A y 
\ FULL OCTET! / 


WHAT IS THE ACTUAL SHAPE OF THE C0 2 SINCE ALL CARBON’S VALENCE ELECTRONS 
MOLECULE? TO ANSWER THIS QUESTION, ARE IN THE POUBLE BONPS, THE BONPS 
USE THIS BRILLIANT PRINCIPLE: MUST POINT PIRECTLY AWAY FROM EACH 

OTHER. 



IN 6UI.FUR TRIOXIPE, $0,, SULFUR ANP 
OXYGEN EACH HAVE SIX VALENCE ELECTRONS. 

tt •« 

. 5 , ,Q; 

t ‘ 

THREE 0XV6GN* CAN BONP TO SULFUR. 




" n 

S: O'- 


11 


USING THE PRINCIPLE THAT ELECTRON 
PAIRS MUST AVOIP EACH OTHER (EXCEPT 
FOR THE ONES IN THE POUBLE BONP- 
THEY’RE STUCW, WE CONCLUPE THAT SO, 
IS TRIANGULAR ANP LIES IN A PLANE. 



(THE POUBLE BONP COULP GO ON ANY 
ONE OF THE OXYGENSJ 


50 



£ARBON TETRA6HL0RIPE, CCL, 

AN INPUSTRIAL SOLVENT, COMBINES 

•C‘ amp :c|* 

i 

WITH FOUR 5JN6LE BONW. 



• • • • •< 
: ci* c *ci- 

* ■ ■ i • • 



FOR MAXIMUM BONP SEPARATION, THIS 
MOLECULE HAS A TETRAHEPRAL SHAPE, 
WITH THE OUTER ATOMS AT THE 
POINTS OF A TRIANGULAR PYRAMIP. 



H 

M 

s 

EXTRA PAIR 



AMMONIA, WH ? . 

yOU MIGHT EX¬ 
PECT THIS TO BE 
A TRIANGLE, BUT 
THE LEWIS 
PIAGRAM SAyS 
OTHERWISE. 

THE FOURTH 
ELECTRON PAIR 
REPELS THE 
OTHERS, ANP WE 
GET A TETRAHE- 
PRON WITH H AT 
THREE OF THE 
VERTICES. 


WATER, H 2 0, IS SIMILAR. IT HAS TWO 
ELECTRON PAIRS WITH NOTHING ATTACHEP 
TO THEM. THEY, TOO, MUST BE TAKEN 
INTO ACCOUNT, 



MOLECULES LIKE NH ? ANP H,0 ARE 
CALLEP BENT. 


THIS COVERS THE SHAPES OF THE MOST 
COMMON MOLECULES, ALTHOUGH THERE ARE 
SOME OPPITIES LIKE SF A , WHERE THE SULFUR 
HAS SIX ELECTRON PAIRS. 



sf 4 is octahepral. 



99 






Shape and Orbital Bond 
Theory (advanced) 

ON THE PREVIOUS TWO PA6E5, WE USEP THE PRINCIPLE THAT ELECTRON PAIRS IN MOLECULES STAY 
AWAY FROM EACH OTHER. WE CAN ACCOUNT FOR THIS FACT IN TERMS OF ELECTRON ORBITALS. 

WHEN H BONPS WITH H, TWO 5 ORBITALS IN O v TWO ELECTRONS IN p ORBITALS ARE 

MERSE. THIS IS CALLEP A O (SI&M/O BONP. SHAREP IN A n (PI) BONP. 


■ flB 

ijllKX '"ySm 



/ ° Ul 




© : |8 















BQR 




Kii 

j 



BUT IN GENERAL, WE SET SOMETHING CALLEP HYBRIP ORPITAL4. FOR EXAMPLE; 


CARBON, WITH fc 2 ^ 2 , HAS TWO WHEN A HYPR06EN ATOM 
PAIREP s ELECTRONS ANP TWO APPROACHES, ITS NUCLEUS 
UNPAIREP p ELECTRONS. PULLS ON C’S ELECTRONS, 

RAISING- THEIR ENER&Y. 


ONE s ELECTRON IS “PROMOTES'* 
TO A p ORBITAL, ANP NOW ALL 
ARE UNPAIREP. 


<=cy 


r O 




THE UNPAIREP ORBITALS “HYBRIPIZE* 
ANP BECOME LOPSIPEP. SUCH AN 
ORBITAL IS CALLEP AN Sp HYBRIP- 
ONE OF THEM LOOKS LIKE THIS. 


ANP FOUR OF THEM LOOK 
LIKE THIS. (HERE EACH ONE IS 
BONPEP TO A HYPROSEN ATOMJ 




f) 

hi 


da* 



THE LOPSIPEP LOBES 
MUST REPEL EACH OTHER, 
SO THE CU A MOLECULE 
MUST BE A TETRAHEPRON. 

THE MOLECULE’4 
GEOMETRY 14 
£AU4EP BY TME 
4HAPE OF HYBRIP 
OR0ITA14- 




More on Lewis Diagrams and 
Charged Molecules 


IN A LEWIS PIA6RAM, EACH ATOM ENPS 
UP WITH A COMPLETE OCTET {USDALLY-SEE 
BELOW;. THIS {an OFTEN HAPPEN IN MORE 
THAN ONE WAY, FOR INSTANCE, WE JUST SAW 
SO,, BUT S0 2 ALSO EXISTS, ANP IS ACTUALLY 
THE MORE COMMON OXlPE OF SULFUR. 


■ i 


it 


: 0 ‘-&r .0 


• * t< 

t_ 


NOTE UNBONPEP PAIR 


SULFUR’S EXTRA ELECTRON PAIR IMPLIES THAT 
THE MOLECULE IS BENT. 



INCIPENTALLY, THE POUBLE 
BONP ISNT REALLY ON ONE 
OXy&EN OR THE OTHER, 
BUT SOMEHOW HALFWAY ON 
BOTH AT THE SAME TIME, 
A QUANTUM-MECHANICAL 
MYSTERY IfNOWN AS 

RESONANCE. 


0*5-0 — 0-5=0 


WE CAN ALSO WRITE A LEWIS PIA6RAM FOR 
SULFATE, so/', WITH NO POUBLE bonps 
AT ALL THIS LOOKS NICE ANP NATURAL, 
EXCEPT THAT TWO EXTRA ELECTRONS ARE 
REQUIREP TO COMPLETE ALL THE BONPS. SO 
SO/' IS REALLY A COVALENTLY BONPEP 
POLYATOMIC ION WITH A CHAR6E OF -2. 



MORE POLYATOMIC IONS= 

" NITRATE, NO/, HAS 

:0 : ONE EXTRA ELECTRON ANP 

'! « , RESONANCE BETWEEN 

: o;; n; o • three afferent forms. 

*• .• 

0 — 0 — o 

0=A-0 O-N-O 0-N=0 

HyPROXIPE, OH', HAS ONE EXTRA ELECTRON. 

' :6 : H 


USUALLY, ALL ELECTRONS ARE PAIREP ANP 
EVERY ATOM 6ETS A FULL OCTET-BUT THERE 
ARE EXCEPTIONS. IN NfTRO&EN PIOXIPE, N0 2 , 
NITROSEN HAS AN UNPAIREP ELECTRON. 


M 


It 


cQ U4i \ 0 : 




ANP IN BERYLLIUM FLUORIPE, BeF 2 , Be &ETS 
ONLY HALF AW OCTET. 

n 

Be: F' 



% • 




“MOSTLY” 
IONIC? WHAT 

is THAT 

SUPPOSEP 
TO MEAN? 


61 






Polarity 

MANY BONPS ARE NOT PURELY 
COVALENT OR IONIC, BUT 
SOMEWHERE IN BETWEEN. 



)\ 


CONSIPER WATER, H 2 0. OXYGEN, WITH AN ELECTRONEGATIVITY VALUE CEN) OF 3-S, 
IS MORE ELECTRONEGATIVE THAN HYPROGEN (£ti * 2.1)* THIS MEANS THAT THE 
ELECTRONS IN THE O-H BONP ARE NOT EQUALLY SHAREP, BUT TENP TO HOVER 
CLOSER TO THE OXYGEN ATOM. 





THE EFFECT OF THIS 
NOT-PURELY-COVALENT 
BONP IS THAT THIS 
MOLECULE HAS POSI¬ 
TIVELY ANP NEGATIVELY 
CHARGEP POLES. THE 
HYPROGEN ENP HAS A 
FRACTIONAL POSITIVE 
CHARGE, WHILE THE 
OXYGEN ENP HAS A 
FRACTIONAL NEGATIVE 
CHARGE, BECAUSE THE 
ELECTRONS ARE CLOSER 
TO ONE ENP. 


•ON AN ARTIFICIAL WALE RANGING FROM 0.7 FOR CESIUM, THE MOST ELECTROPOSITIVE ELEMENT, TO 
A.0 FOR FLUORINE, THE MOST ELECTRONEGATIVE. 


C2 



r -—-— 

A BONP LIKE O-H, IN WHICH TME ELECTRONS ARE CLOSER TO ONE ENP, IS 
CALLEP POLAR. POLAR BONPS ARE INTERMEPIATE BETWEEN COVALENT BONPS 
(EQUAL SHARING ANP IONIC BONPS COMPLETE TRANSFER OF ELECTRONS}. 


IONIC STRONGLY POLAR WEAKLY" POUR COVALENT 



THE POURITY OF BONPS AFFECTS THE WAY CHARGE IS P1STRIBUTEP OVER A 
MOLECULE. 

^ _ 


A BONP’S POURITY 
PEPENPS ON THE 
PIFFERENCE IN 
ELECTRONEGATIVITY 
BETWEEN TWO ATOMS. 
BIGGER PIFFERENCES 
MEAN MORE POURITY, 
WITH A PIFFERENCE OF 
1.0 OR MORE BEING 
CON5IPEREP IONIC. 


SAMPLE ELECTRONEGATIVITIES 

H 2.1 


Na 0.9 

U 1.0 


Mq 1.2 

C 25 


5 25 

N 3,0 


a 3.0 

0 35 


K 05 

F 4.0 


Ca 1.0 


BONP 

EN PIFF. 

BONP TYPE 

N=N 

0 

COVALENT 

C-H 

0.4 

ESSENTIALLY COVALENT 

0- H 

1.4 

MOPERATELY POUR 

H —F 

1.9 

STRONGLY POUR 

Li—F 

3.0 

IONIC 









THE POURHY OF WATER EXPLAINS some of its familiar properties, for 
INSTANCE: 


WATER is liquip at 
room temperature. 

TME PARTIAL CHAR6ES 
AT EACH ENP OF A 
WATER MOLECULE 
MAKE THE MOLECULES 
ATTRACT EACH OTHER, 
ENP TO ENP. WATER 
BOM PS WEAKL/ TO 
ITSELF. THIS INTERNAL 
COHESION HOLPS 
WATER TOGETHER IN 
LIQUIP FORM. 


H* ' H + 

x c/ 


H* 


/°v 

n «* * 


ETC. 


/°\ ♦ 

< X X 

O' -D 

V V s * 4 

X) X 0( H 6- 

T H;J *v' " 


By CONTRAST, THE MUCH HEAVIER BUT LESS POUR l >0 1 HAS LITTLE MUTUAL 
ATTRACTION, SO IT FORMS A 6AS AT ROOM TEMPERATURE. 


POURITY ALSO EXPLAINS 
WHy WATER IS SO 600P 
AT PISSOLVIN6 IONIC COM- 
POUNPS SUCH AS TABLE 
SALT. THE CRySTAL’S IONIC 
BONPS SLOWLy £IVE WAy 
TO THE PULL OF WATER’S 
POLES, AS IONS BREAK 
OFF THE CRySTAL ANP 
ATTACH THEMSELVES TO 
WATER MOLECULES. 




SIMlURLy, THE WEAK ATTRACTION OF A POUR H TO ANOTHER MOLECULE IS 
CALLEP MyPROSEN BONPIN6. IT HAPPENS TO BE A KEy FEATURE OF THE 
CHEMlSTRy OF LIFE (SEE PA6E 241). 


64 


IONIC, COVALENT, METALLIC THESE ARE THE 
MAIN TYPES OF CHEMICAL BONPS. WE’VE SEEN 
HOW THESE INTERATOMIC INTERACTIONS ARISE 
FROM THE ELECTRICAL. PROPERTIES OF ATOMS, 
ANP HOW THEY AFFECT THE STRUCTURES OF 
SUBSTANCES. NOW WE WANT TO w w A 
FINP OUT WHAT THE/ HAVE TO 
PO WITH THE CHEM... 

<EX£U$E ‘ 

2 : MEW , 


& 










66 


Chapter 4 

Chemical Reactions 

OOPS/ SOMEHOW WE FINE? OUR SELVES MAROONEP ON A PESERT ISLANP. HOW 
ARE WE &OIN6 TO SURVIVE? MAXBE WE CAN MAKE SOMETHING USEFUL OUT 
OF THE MATERIALS AT HANP... 



67 


Combustion^ Combination, 
Decomposition 



LETS write A REACTION EQUATION for 
FIRE. WOOP CONTAINS MANy PlFFEREMT MA¬ 
TERIALS but its MAiNLy maps of C, h, anp 
O IN THE RATIO 1:2*4. WE CAN WRITE THE 
EMPIRICAL FORMULA FOR WOOP AS CH 2 0, ANP 
THEN FIRE LOOKS LIKE THIS4 

CH 2 0 (s) + O z Cq) ^ C0 2 (q) I + H 2 0 Cq)\ 


THE NOTATION EXPLAINER; THE SUBSTANCES ON THE 
LEFT OF THE HORIZONTAL ARROW — ARE CALLER 

REACTANTS. on the risht are the REACTION 
PRODUCTS. -*♦ WILL MEAN THAT HEAT WAS 
APREP. THE SMALL LETTERS IN PARENTHESES 
SHOW THE PHySICAL STATE OF THE CHEMICALS-. 
q - &AS-, s = SOUR; l * LlQUlP; aq = RISSOLVEP 
IN WATER. 1 MEANS AN ESCAPING 6AS. ANP I WILL 
MEAN A SOUR SETTLING OUT OF SOLUTION, OR 

PRECIPITATING 




SO OUR EQUATION REAPS*. 
SOUP WOOP PLUS 
GASEOUS OXy&EN ANP 
HEAT MAKES SASEOUS 
CARBON PIOXIPE PLUS 
WATER VAPOR. THIS IS A 
TypiCAL COMBUSTION 
REACTION, (you can 
TEST FOR THE WATER By 
H0LPIN6 A COOL &LASS 
OVER THE FLAME; 
PROPLETS WILL 
CONPENSE ON IT.; 



‘WE’RE LEAVIM6 OUT PARTIALLy OR WHOLLY NOH«>MBU$TEP PRODUCTS SUCH AS WOT, SMOKE, CO, ETC 






MOW THAT WE HAVE FIRE, WE’LL 
MAKE A BETTER FUEL'- CHAR¬ 
COAL- WE PUT PRY WOOP AMP 
COCONUT 5HELLS IN A PIT CTO 
LIMIT AVAILABLE OXY&EN) ANP 
FIRE IT UP. THE REACTION IS* 

CW 2 0 -A. CCs) + H 2 0G})T 

this 15 A PE COMPOSITION 
REACTION (OF THE FORM 
AS — A + B;. IT MAKES ELEMEN¬ 
TAL CARBON, OR CHARCOAL. 


WE BUILP A STONE STOVE ANP FUEL IT WITH 
CHARCOAL. CHARCOAL’S COMBUSTION 15 A 
COMBINATION REACTION (A+-B — AB> 

CCs) + 0 2 (<j) - C0 2 Cq)] 



IN THI5 OVEN WE CAN MAKE POTTERy. WE 5COOP A FlNE-SRAINEP MINERAL, 
KAOLINITE, FROM THE LAKE BOTTOM ANP &RINP IT WITH A LITTLE WATER TO 
MAKE A 5MOOTH KAOLIN CLAY, Al 2 Si 2 0 5 (0H) 4 . WE 5HAPE THI5 INTO VE55EL5 
ANP FIRE THEM IN A HOT OVEN-. 


3Al 2 Si 2 0/0H ) 4 ( 5 ) -A* Al^O^Cs) * 4Si 0 2 Cs) + 6W 2 0 Cq)] 



THE FIRST PROPUCT IS 
CALLEP MULUTE- THE 
SECONP, Si0 2 , IS 
SILICA, OR SANP-ANP 
MELTEP, IT’S 6LASS. 
WHEN THE CLAY IS 
FIREP, MU LLITE FUSES 
WITH THE OLASSY SILICA 
TO FORM A VERY HARP, 
WATERPROOF POT. 



‘MORE OR t£5*. A6AIN W£ I6NORC TRA££ REA£TANT$ ANP PRODUCTS. 


69 




Balancing Equations 

NOTE THAT SOME OF THE SUBSTANCES IN THE POTTER/ REACTION HAVE NUMERICAL 
COEFFICIENTS IN FRONT OF THEM. THE EQUATION MEANS THREE MOLECULES OF 
KAOLIN CLAY YIELP ONE MOLECULE OF MULLITE, FOUR OF SILICA, ANP SIX OF WATER. 

3At 2 ^0/0W 4 (s) Al^i lOnCs) + 4*0*60 + (M 2 OCq)] 

THE COEFFICIENTS BALANCE THE EQUATION. THE SAME NUMBER OF EACH KINP OF 
ATOM APPEARS ON BOTH SIPES: 6 Al, 6 Si, 27 0, ar\d 12 H. HOW PO WE FINP 
THESE COEFFICIENTS? 

L R 

START WITH AN UNBALANCE? EQUATION 
ALjSLjO^OH), (s> ^ Al^St^Ojj 6) + Si0 2 (s) + H 2 0 Cq}] 

WRITE POWN THE NUMBER OF ATOMS ON EACH SI PE- 

BALANCE ONE ELEMENT. WE START WITH Al, 

MULTIPLY BY 3 ON THE LEFT TO 6ET- 

3 Al 2 Si 2 0/0H) 4 (s) -A* Al^O^CO + Si0 2 (s> + H 2 0 Cg)f 

A6AIN COUNT ATOMS ON EACH SIPE- 


L R 




BALANCE ANOTHER ELEMENT. WE CAN BALANCE 
Si BY PUTTING A 4 IN FRONT OF Si0 2 = 

3 A! 2 Si 2 0 5 (0H) 4 <0 ± Al*Si 2 0 B (s) + 4Si0 2 (s) + H 2 0 (q)\ 

A6AIN COUNT ATOMS ON EACH SIPE. 



FINALLY, A 6 IN FRONT OF H 2 0 BALANCES 
BOTH H ANP 0. 

3AI 2 Si 2 O 5 (0H) 4 6) -A. Ai 4 Si 2 0 1? ($) + 4Si0 2 (s) + SH 2 0 Cq>T 



70 




• WRITE THE EQUATION WITHOUT 

COEFFICIENTS. 

• LIST THE ELEMENTS IN THE EQUATION. 

• CHECK THE NUMBER OF EMM KINP OF ATOM 

ON BOTH SIPES. 

• BALANCE ATOMS ONE ELEMENT AT A TIME By 

APJUSTIN6 COEFFICIENTS. 

• REPUCE TO LOWEST TERMS IF NECESSARY 


THE ACT, OR ART, OF BALANCING EQUATIONS IS CALLEP REACTION 
STOICHIOMETRY. 


HERE ARE SOME PRACTICE EXAMPLES. SUPPLy COEFFICIENTS IN EACH EQUATION. 



Al(s) + Fe 2 0 3 (s) Al 2 0,(s) + FeCs) 


KClO/s) -A. me s) + 0 2 Cq) 

C A W w Cq> + O z Cq) — C0 2 (g) + H 2 0<g) 

W 2 (g) + H 2 (g) — NH,(g? 

? 4 (s) + F 2 (g) — PF 5 (g) 

Zn(N0,) 2 (s) ^ ZnO(s) + N0 2 (g)+ 0 2 Cg) 

H,P0 4 fl) -A, H 2 OC) + P 4 0 1(? Cs) 

£u(s) + AgNO ? (aq) — » Cu(N0 3 ) 2 (aq) 4 - Aqj 

FeCs) + 0 2 (<j> — Fe 2 0 ? ts) 

FeCl/s) + H 2 0(0 — HC! (aq) + FeCOH^I 


71 



The Mole 



THE EQUATION'S COEFFICIENTS LET 
US FINE? THE RELATIVE MA$$£$ OF 
PRODUCTS ANP REACTANTS. THE 
CALCULATION USES A UNIT CALLEP 
THE MOlE- ONE WOLE OF A 
SUBSTANCE IS THE AMOUNT WHOSE 
MASS EQUALS THE MOLECULAR OR 
ATOMIC WEIGHT OF THE SUBSTANCE 

EXPRE54EP IM 6RAM*. 


THAT’S KINP OF A MOUTHFUL FOR A SIMPLE IPEA. LETS ILLUSTRATE By EXAMPLE'. 


a 

MOLECULAR* WEIGHT 

MOLAR WGl&WT 


52 AMU 

32 SRAMS 

Si0 2 

bO AMU 

bO SRAMS 

Al 2 Si 2 0 5 (0H) 4 

250 AMU 

159 SRAMS 

Fe 

5b AMU 

5b SRAMS 

PROTON 

1 AMU 

1 SRAM 

NaCl 

59.5 AMU 

50.5 SRAMS 



(NOTE; HERE MOLECULAR WGI&HT REALLY MEAN* THE MA** OF A BA*IC PARTICLE OF THE SUBSTANCE 
EXPRESSEP JN AMU. IN AN IONIC CRYSTAL LIKE NaCl, WE MEAN A SASIC COMPONENT OF THE CRYSTAL- 


THE MOLE IS USEP TO SCALE UP FROM ATOMIC PIMENSIONS TO METRfC WEIGHTS. 
TO BE PRECISE, A SRAM IS ABOUT bOl,100,OOO,OOO,OOO,OOO,OOO,OOO BISSER 
THAN AN AMU. THAT IS, 1 q = 0.022 X 1(T* AMU. 



THIS THEN, IS THE NUMBER OF 
PARTiae* IN A MOLE- A mole 

OF ANYTHING HAS THIS MANy 
PARTICLES/ (>.011 X IS 2 * IS CALLEP 

AV06APR0’* NUMBER, after 

AMEPEO AVOSAPRO, WHO FIRST 
SUSSESTEP THAT EQUAL VOLUMES 
OF SAS HAVE EQUAL NUMBERS OF 
MOLECULES. 




r\ 

NOW SUPPOSE I START WITM 1 00 kg OF Cl Ay. NOW MANY KILOGRAMS OF 
POTTERY WILL- I 6ET? WE START WfTM TME 8ALAN££P EQUATION; 

3 Al 2 $i 4 0 5 <0H) 4 (s') Al^OjjCs? + 4$i0 1 C«) + 6H 2 0(g>t 


THE cwy THE POTTERy 



THEN WRITE A MA$$-0ALAN£E TABIE, SMOWIN6 THE NUMBER OF C? RAM* OF 
EA£H REACTANT ANP PROPUOT; 

REA£TAWTS MOLAR WEI6HT PROPUC V? MOLAR WEIGHT 


3 MOL A!jSi 2 0 5 (0W 4 

3 X 256 = 774q 

1 MOL Ai 6 SijO„ 

426 q 



4 MOL Si 0 2 

4 X AO * 240 q 



6 MOL H 2 0 

6 X 10 - 1O0q 

TOTAL 

774 g 

TOTAL 

774 q 


THIS SAYS 774 q OF KAOLIN CLAY MAKES 426 + 240 = 666 g OF POTTERY. 

SO 1 g KAOLIN MAKES (666/774)% = 0.86 q OF POTTERY 

ANP 100 kg MAKES (O.06)(1OOVq)(\OOO q/\cq) = 06,000 g * 06 kg. 

WE £AN EQUALLY WELL 
WORK BA£KWARP. IF WE 
WANT 100 kg OF POTTERY, 

HOW MU6H WET ClAY 
SHOULP WE MIX UP? £ANS= 

(100X774/666) kgj 



7? 
















More Reactions 

— 

WEVE MAPE VESSELS ANP A STOVE. MOW LET'S £OOK UP SOME &UILPIN6 
MATERIAL*. WE HEAT LIMESTONE, ^halk, amp/or seashells, which are all 
MAPE OF CALCIUM CARBONATE, CaC0 3 . THE PROPUCT IS QUICKLIME, CaO. 


CaC0 9 ($) CaO (s) + CO z Cq)] 



WE aM EVEM PAINT OUR HOUSE. 

WHITEWASH, OR *LAKEP LIME, 

CaCOW z , COMBINES CaO ANP H 2 0: 

CaO (s') + H 2 0 (0 — Ca(0U\(aq) 
SLAKEP LIME ALSO MAKES A &OOP 

purry amp mortar... anp over time, 

WHITEWASH SLOWLy COMBINES WITH 
CO z FROM THE AIR ANP HARPENS INTO 
A WHITE, STUCCO-LIKE MATERIAL; 

CaCO^Cs) + 00/ 9 ) - CaCO^Cs) + H 2 0(q)l 

LIMESTONE 

A6AIM! 



74 




MOW LET’S MAKE 40AP, SO WE CAN WASH UP. 


FIRST BURN SEAWEEP TO 
GET A WHITE, POWPERy 
MlXURE OF Na 2 CO ? (SOPA 

ash; anp k 2 co ? (potash/ 

SEPARATE OUT THE SOPA 
ASH (NEVER MINP HOW/ 



WE BOIL SOME WILP 
BOAR FAT WITH THE 
CAUSTIC LYE- THE FAT 
WILL NOT PISSOLVE IN 
WATER, BUT THE 
SOPlUM IONS PUT A 
POUR “TAIL” OM THE 
FAT MOLECULE, ALLOW¬ 
ING IT TO INTERACT 
WITH WATER IN A 
SOApy WAy. WHAT’S 
THE REACTION? 


COMBINE SOPA ASH WITH 
WHITEWASH TO MAKE THIS 
REACTION: 

Ca(0H) 2 (aq) + Na 2 C0 ? (aq) 


INaOHCaq} + UCQJ*)\ 


A WHITE CLOUP OF UC0 3 
SETTLES TO THE BOTTOM. 
PECANT—CAREFULLy/—THE 
CLEAR NaOH SOLUTION. 
THIS is CMVX\C LYE, 
STRONG STUFF/ 



Ohhhhhhhhhhhhhhh 

U II * \ t I \ ! I * I I t I I 1 * 

-C'C-C-C-C-C'C-C-C-C-C-C'C -H 

, s , v 111 t I I I 1 I I I * I I I 

H nMMHHMHHMHMHHHMH 

j 

H-C-0-C'(CHj) m CH 3 

U"C-0'C-(CU 2 ) 14 CU ? \ 


^ 3 NaOH 


C-OH „ 

H" I ^ H H H HH HHHHHHHHHH 

1 n i i i ill ill i t i i 

H-C-OH + ma.-0-C-C-C-C-C-C--C'C'C-C-C-C-C-C~C--C~U 

I hhhhhhhhhhhhhhh 

.C'OH \ 


A CRUPE SOAP 


v_ GLyCEROL (A GOOV 
SKIN CONPITIONER; 


79 










r 


Redox Reactions 


NOW LET'S MAKE SOME 
FLARES, SO WE CAN 
SIGNAL PASSING SHIPS. 
THIS WILL REQUIRE 

EXPLOSIVE POWDER. 

ITS IN6REPIENTS ARE 

CUARCOM, SULFUR, 

ANP POTASSIUM NITRATE 

or SALTPETER, mO v 



WE ALREAPy HAVE CHARCOAL... SULFUR WE SCRAPE UP IN ELEMENTAL FORM FROM 
THE NEARBY VOLCANO (IT’S THE YELLOW STUFF;... K IS IN POTASH, AMP 
NITRATE WILL COME FROM Ca(N0 ? ) 2 , WHICH WE FINP IN PAT 6UANO- 








BOIL THE 6UANO IN WATER 
WITH POTASH ANP 6ET A 
POUB LE-PISPLACEMENT 
REACTION: 

Ca(NO ? ) 2 (aq) + K 2 C0 ? (aq) 


CaCO, (s?l + 2<NO,(aq) 


THE CHAU 
SETTJ.S5 
OUT OF 
■5OLUTJ0M. 



WE CAREFULLY PECANT 
THE SOLUTION OF KNO ? . 



LET THE WATER EVAPO¬ 
RATE ANP WE ARE LEFT 
WITH A MASS OF NEEPLE- 
LIKE CRySTALS OF KNO r 



76 











WMAT WILL THE REACTION PROPUCTS BE WHEN WE SET THIS STUFF OFF? 


C + S + KNO ? — ?? 

rr TURNS OUT THAT WE 
CAN MAKE A GOOP GUESS 
AT THE PROMTS By FOL¬ 
LOWING the ELECTRONS. 

EXPLOSIONS BELONG TO 
AN IMPORTANT CLASS OF 
REACTIONS INVOLVING THE 
TRANSFER OF ELEC¬ 
TRONS FROM ONE ATOM TO 
ANOTHER. SUCH REACTIONS 
ARE CALLEP OXIPATION- 
REPUCTION REACTIONS, 
OR REPOX FOR SHORT. 



EXAMPLE IN COMBUSTION, 

C + 0 2 —* C0 2 , 

FOUR ELECTRONS MOVE 
FROM C TOWARP THE TWO 
0 ATOMS. WE SAX C IS 
0XIPI2EP. o, WHICH 
GAINS ELECTRONS, IS 
REPUCEP- ANOTHER 
EXAMPLE IS RUSTING, OR 
CORROSION: 

4fe + 30 2 — 2F@ 2 0 ? 

Fe SHEPS ELECTRONS ANP 
IS OXIPIZEP-, 0 GAINS 
THEM ANP IS REPUCEP. 

NOTE: OXYGEN ITSELF 
NEEP NOT BE INVOLVEP/ 
OXIPATION MEANS THE 
TRANSFER OF ELECTRONS 
TO ANY ATOM/ 


3 « AS IN 

H 2 + S —» H 2 S, I - 

WHERE H IS OXIPIZEP, ANP 
SULFUR IS.. UGH... REPUCEP! 




h 2 s, rotten 

EGG GAS 







77 






Oxidation Numbers 

HOW MANy ELECTRONS POE* EACH ATOM &AIN OR LOSE? 


the OXIPATIOM STATE or OXIPATIOM NUMBER of am element in a 
COMPOUNP SHOW* IT* SURPLUS OR PEFICIT OF ELECTRON!*. THAT I*, THE OXI¬ 
PATIOM number IS THE NET £MAR£E ON THE ATOM-* for instance, im 
CaO, Ca HA* THE OXIPATION NUMBER 4-2-IT 6IVES AWAY TWO ELECTRONS— 
AMP O’* OXIPATIOM NUMBER I* -2, BECAU*E IT ACCEPT* TWO. 




1} THE OXIPATION NUMBER OF AN ELEMENT IN 
ELEMENTAL FORM IS ZERO. 

Z) SOME ELEMENTS HAVE THE SAME OXIPATION 
NUMBER IN ALMOST ALL THEIR COMPOUNPS; 

• H> +1 (EXCEPT IN METAL HYPRIPGS LIKE 
NaH, WHERE IT’S -1) 

• ALKALI METALS Li, Ma, K, ETC.: +1 

• 6R0UP 2 METALS Be, Mq, ETC.: +2 

• FLUORINE; -1 

• OXY&EN: ALMOST ALWAYS -2 

3) IN A NEUTRAL COMPOUNP, THE OXIPATION 
NUMBERS APP UP TO ZERO. 


4) IN A POLYATOMIC ION. THE OXIPATION NUM¬ 
BERS APP UP TO THE CHARGE ON THE ION. 


*0R WHAT IT WOULP BE, IF THE BONR WERE FULLY 10N/C. IN ASSICNIN6- OXIPATION NUMBERS, WE PRETENP 
THAT THE ELECTRONS ARE COMPLETELY TRANSFERRER FROM ONE ATOM TO ANOTHER, EVEN THOU&H IN 
REALITY THEY MAY BE ONLY UNEQUALLY SHARER 


79 



AN ATOM’* OXlPATION NUMBER PEPENP* ON THE OTHER ATOM* AROUWP IT. 
FOR JN*TANCE, (N WCX, CHLORINE ACQUIRE* ONE ELECTRON (FOR AN OXlPATION 
*TATE OF -1 ) BECAU*E C\ I* MORE ELECTRONEGATIVE (EM - 3.0) THAN 
HYPROGEN (EM * 2.1), 


BL»T IN THE 
PERCHLORATE 
ION, C10 4 \ CHLORINE 
HA* AN OXlPATION 
NUMBER OF +7, ALL 
IT* VALENCE 
ELECTRON* GO TO 
OXyGEN, WHICH I* 
EVEN MORE ELECTRO¬ 
NEGATIVE (EM * 35) 
THAN CHLORINE. 


HERE ARE *OME ELEMENT* ANP THEIR COMMON OXlPATION NUMBER*. THE 
BIGGER THE PLU*, THE MORE OXIPIZEP. 




MO*T REPUCEP 

INTERMEPIATE 

MO*T OXIPIZEP 

H 

NiH 2 (-1) 

M 2 Co) 

h 2 o, oh- (+i ; 

C 

ch 4 (-4; 

c Co) 

co 2 , co, 2 ' (+4; 

0 

H 2 0, C0 2 , 

CaO, ETC. (-2) 

h 2 o 2 m; 

(H/PRO&EN PEROXIPE) 

o 2 (cO 

N 

NH, (-3) 

n 2 Co), n 2 o (+1 

NO (+2) 

no,' (+5; 

* 

H 2 *, K 2 * (-2) 

* Co), *o 2 (+4; 

*0,, *0/" (+6) 

Fe 

Fc CO) 

FeO (+2) 

Fe 2 0, M) 

Cl 

hci h; 

Cl 2 (<?) 

C\0 A (+7) 


» OXlPATION 

REPUCTION « 


79 



























JKl REPOX REACTIONS, SOME SUBSTANCES-RE PU£ I A6ENT5 OR 

REPU£TANT6— ponate electrons, anp OTWERS-OXIPIZ1N6 A6£NT$, 
OR OXIPAMT^ain them. 


WAIT—THE OXlPJZINS 
A6-ENT IS REPUCEP 
ANP THE R6PUCINS 
ASENT IS OXIPIZEP? 




/-—-\ 

&OIN6 BACK TO THE EXPLOSIVE BLACK POWPER, WHAT ARE THE MOST LIKELy 
OXIPIZIN6- ANP REPUCINS A6ENTS? LETS IGNORE THE SULFUR FOR THE TIME 
BEIN6 ANP CONCENTRATE ON THE CARBON ANP SALTPETER: 

C + KNO ? — ? 

OF THOSE FOUR ELEMENTS, WE CAN ELIMINATE X ANP 0, BECAUSE THEY ARE 
ALREApy FULLy OXIPIZEP (K AT +1 ) ANP REPUCEP (0 AT -V RESPECTIVELY IT 
IS VERy HARP TO OXIPIZE O 2 ' OR REPUCE K + / BUT C (£?) CAN BE OXIPIZEP 
TO +4 AS EITHER C0 2 OR CO/", ANP N 05) CAN BE REPUCEP TO 0 AS N 2 . 

SO WE EXPECT SOMETHING LIKE THIS BEFORE BALANCING 

&s) + KNO/s) — CO z Cq>] + M 2 Cg)| + K/O/s) 

V___' 



WE CAN BALANCE THIS BY FOLLOWING THE ELECTRONS: EACH MOL OF C CIVES 
UP 4 MOL ELECTRONS, ANP EACH MOL OF N ACCEPTS 5. THIS BALANCES IF lO 
MOL ELECTRONS MOVE FROM SC TO 4N. (WE CET THE OTHER COEFFICIENTS By 
BALANCING K ANP 0.) 


tCCs) + 4KNO,(s) 


?C0 2 (q)I + 2N,(q)j + M % CO£d 


THIS REACTION WILL 
ACTUALLY PROPUCE A 
PRETTY COOP FIZZ, 
BUT CENTURIES OF 
EXPERIMENT HAVE 
SHOWN THAT APPINC 
SULFUR MAKES A 
MUCH BI CCER POP. 


W SULFUR IS 
r 60UP6N' OR 

YELLOW, ANYWAY.. 



ELEMENTAL S (0), REPUCES EASILY TO -2 IN K 2 S. IN FACT, CHEMISTS NOW 
KNOW THAT FORMINC K 2 S IS “EASIER” THAN FORMINC K 2 C0 ? . POINC SO 
CONSUMES LESS ENERCY—ANP LEAVES MORE ENERCY TO POWER THE BANC. 
SO WE EXPECT SOMETHINC LIKE: 


ad + KNO/s) + S td 


COX q)j + N 2 (q)f + K 2 S(s) 


EA£H C LOSES 4 

ELEZTROMS 


EACH N WINS 5 
ELECTRONS 


EACH S SAINS 2 
ELECTRONS 


THIS BALANCES WHEN 3 MOLS C CIVE UP 12 MOLS ELECTRONS, OF WHICH IP MOLS 
ELECTRONS CO TO 2 MOLS N ANP 2 MOLS ELECTRONS CO TO ONE MOL S: 

tad + 2KNO/s) +■ S(s) — tC0 2 Cq)l + N 2 (q) | + K 2 S(s) + &AM6/ 


) 



WOW WE CAN MAKE A FORMULA FOR BLACK POWPER. WE START WITH THE 
MASS-BALANCE TABLE: 


REACTANTS MOLAR WEIGHT PROPUCTS MOLAR WEJ6HT 


3 mol C 

3 X 12 = 36 g 

3 mol £ 0 ^ 

3 X 44 = 132 9 

2 mol KNO ? 

2 X IOI =202 g 

1 mol 

20 q 

1 mo! $ 

32 q 

1 mol K 2 S 

110 9 

TOTAL 

270 9 

TOTAL 

270 9 


FOR OME 6RAM OF POWPER, WE NEEP (36/270) q = 0.13q C, (202/270) 9 = 
0 .75q KNO,, ANP (32/270) q - 0.12 9 5. MULTIPLy By 1 00 TO SEE WHAT 
WE WEEP TO MAKE 100 q OF POWPER: 



13 q CARBON 
75q SALTPETER 0<H 0,). 
12q SULFUR 



f 

MOT BAP ! A CLASSIC &UMPOWPER RECIPE CALLS FOR 10q SULFUR, 15q CARBON, 
AMP 75 q SALTPETER. THE PlFFERENCE FROM OUR RESULT IS PUE TO TRACES 
OF OTHER REACTION PROPUCTS THAT WE WE6LECTEP. THE REAL RECIPE IS A 
PROPUCT OF TRIAL ANP ERROR. 



















NOW WE MIX SOME OF 
THIS STUFF UP... 





if you TRy THIS 
AT HOME (NOT 
RECOMMENPEP 

IN THE FIRST 

place;, ALWAys be 
SURE TO GRIND 
THE INGREDIENTS 

SEPARATELY— 

UNLESS you WANT 
TO BLOW OFF yOUR 
FINGERS, OR EVEN 
yOUR WHOLE HAND. 



>ACK OUR POWDER INTO BAMBOO TUBES, AND—SAy, HERE COMES A SHIP.' 
T THE FUSE! 


X X'' 



V'* 


x. 





AHOy/ 








Chapter 5 

Heat of Reaction 


|n THE LAST 
CHAPTER, WE 
LOOKED* AT 
£HEMI£AL 
REACTIONS AS 
TRANSFERS OF 
MATTER. WE 
KEPT A CAREFUL 
A^OUNTINfr OF 
ATOMS AS THEy 
REARRAN&EP 
THEMSELVES. 

NOW WE LOOK 
AT REACTIONS 
ANOTHER WA* 
AS TRANSFERS 

OF ENERGY. 


” V) 


ENERGY? 
WHAT ENER&y? 


JEA. 


W 










PHYSICISTS PER ME EMER&y MECHANICALLY, AS THE ABILITY TO PO WORK * WORK 
IS WHAT HAPPENS WHEM A FORCE OPERATED OM AM OBJECT OVER A PISTANCE-- 
WORK * FORCE X PISTANCE. THE METRIC UNIT OF ENER&Y ft THE NEWTON-METER, 

or JOULE. 



1 JOULE = WORK PONE <&i A FOR^E OF ONE NEWTON OPERATING OVER A PISTANCE OF ONE METER. 


CHEMIST* CARE 
ABOUT WORK, TOO 
(AN EXPLOSION POES 
WORK), BUT WE 
ALSO CARE ABOUT 
OTHER FORMS OF 
ENER&Y: CHEMICAL 
ENER&y, RAP1ANT 
ENERGY, ANP MEAT. 
EACH OF THESE HAS 
THE ABILITY TO PO 
WORK. 



RAPIANT ENER&y 
HEAT5 5ANP 

Y 

SANP HEAT* AIR 

Y 

M.OT AIR RI5E5 
(WORK; 


RAPIANT ENER&y 
FROM $UN 

Y 

4UEMICAL PRO- 
t&rtV? IN PLANT 
(PH0T06yNTHE$l5, 
ET a 


PLANT GROWTH 

work; 


ONE KINP OF ENERGY CAN BE CONVERTEP INTO ANOTHER KINP, BUT ENERGY IS 
NEVER CREATEP OR PESTROYEP. THAT’S A LAW-THE LAW OF CONSERVATION 

Of ENER6* 


06 


*UOT TO &E COMFUSEP WITH USEFUL WORK. 









LET'S EXAMINE MECHANICAL ENERGY MORE CLOSELY. IF I PUSH THIS COCONUT, IT 
MOVES... ANP THE LONGER ANP/OR HARPER I PUSH, THE FASTER IT GOES. (THIS 
IS CLEARER IN OUTER SPACE, AWAY FROM FRICTION ANP GRAVITY.; BY POING 
WOR< ON THE COCONUT, I APP ENERGY TO IT: KINETIC ENER^y (K-G-), THE 
ENERGY OF MOTION. 



BACK ON EARTH, I 
PUSH THE COCONUT 
AGAIN, BUT IN AN 
UPWARP PIRECTION. 
THE COCONUT FLIES 
UP, BUT IT SLOWS 
UNPER THE PULL 
OF GRAVITY. EVEN¬ 
TUALLY IT STOPS 
ANP BEGINS TO 
FALL WHAT BECAME 
OF THE ENERGY I 
APPEP?? 


^TATJOKJARy, 
NO K.G., 
W&U ?£. 


LOW SPEEP, 
SOME K.E., 
SOME ?£> 


mu SPEEP, 
mu K£. 




t# 

,v O 



AS THE COCONUT 
SLOWS ANP LOSES 

ice., rr sains 

POTENTIAL 
ENERCy fp.E.;. 

THIS IS ENERGY 
THAT PEPENPS 
ON THE BOPY’S 
POSITION IN THE 
EARTH’S GRAVITA¬ 
TIONAL FIELP- 
K.E. + P.E. IS 
CONSTANT. 


IT TURNS OUT THAT ALL FORMS OF ENERGY CAN BE UNPERSTOOP IN TERMS 
OF KINETIC ANP POTENTIAL ENERGY- RAPIANT ENERGY, FOR INSTANCE, IS THE 
K.E. OF MOVING PHOTONS, OR LIGHT PARTICLES/ THERE IS POTENTIAL ENERGY 
STOREP IN CHEMICAL BONPS. ANP HEAT IS... HEAT IS... WHAT 15 HEAT, ANYWAY? 



THE tf&HT” WEEP WOT BE VISIBLE. MOVIW6 PHOTONS CONVEY THE EWER6Y OF ALL ELEOTROMA&WETIC 
RAPJATION, FROM X-RAYS TO RAPIO WAVES. 


87 





MEAT, WE KNOW, MAS SOMETHING 

to po witm TEMPERATURE, anp 

TEMPERATURE IS FAMILIAR ENOUGH. 
WE EVEN KNOW HOW TO MEASURE 
IT, WITH A THERMOMETER. 


CV&m SZALE 
1 00 ° - 


50° —1 



KELVIM SZALE 
- 373.15° 


323 . 15 ° 


273.15° 


THE UNITS ARE PE6REES CEL¬ 
SIUS ra THE CELSIUS 5CALE SETS: 

OX * MELTING POINT OF WATER 
\OOX * SOILING POINT OF WATER 

THE KELVIN SCALE HAS PE6REES 
THE SAME SIZE AS CELSIUS, BUT 
STARTS LOWER: 

0°K - ABSOLUTE ZERO, WHERE 
ALL MOLECULAR ANP ATOMIC 
MOTION STOPS * -273.15°C. 


COLLOOUIALLy, WE SAy SOMETHING IS 
HOT WHEN WE REALLy MEAN IT MAS A 
HI6H TEMPERATURE. A CHEMIST WOULP 

never SAy this.' HEAT ANP TEM¬ 
PERATURE ARE NOT THE SAME. 



TO ILLUSTRATE THE PIFFERENCE, 
SUPPOSE WE COOK TWO COCONUTS, 
RAISING THEIR TEMPERATURE By 75°C 
(FROM 25° TO 1 0O a , SAy). THEN THE 
TWO COCONUTS TOGETHER HAVE THE 

SAME TEMPERATURE CHANGE 

AS ONE COCONUT, BUT THEy ABSORB 
TWICE AS MUCH HEAT, BECAUSE 
THEy CONTAIN TWICE AS MUCH MATTER 
TO HEAT UP. 



SAME TEMPERATURE CHANGE 
ROUBLE THE HEAT ZHANSE 


WHAT, THEN, IS THE RELATIONSHIP 
BETWEEN TEMPERATURE ANP HEAT? 


X = °K - 273.15 


ee 


TO BEGIN WITH, 
WHEREVER WE 
LOOK, HEAT 
TRANSFER* ARE 
ASSOCIATE? WITH 
TEMPERATURE 
DIFFERENCE*. 

WE KNOW FROM 
EXPERIENCE THAT 
HEAT FLOWS FROM 
HOT TO COLP. 


/ IT’S AN ENER&y > 
f CHANGE THAT 
INVOLVES NO VISIBLE 
WORK OR MOVEMENT/ 


yow/ WHO 
SAys? 


PE 



£ 


i, Sf /•> 


THAT IS, WHEN A HIGHER-TEMPERATURE OBJECT MEETS A LOWER-TEMPERATURE 
OBJECT, ENER^y FLOWS FROM THE WARMER ONE TO THE COOLER ONE UNTIL 
THEIR TEMPERATURES EQUALIZE. AN EXAMPLE IS WHEN WE IMMERSE SOME¬ 
THING COOL IN HOT WATER. (ASSUME THAT THE “SOMETHING" POES N’T MELTJ 




INITIAL STATE 
T 2 < T, 


HEAT FLOW 
TAKES PLACE 



FINAL STATE 

"^2 < ”^FINAL < ^I 


(FINAL TEMPERATURES ARE EQUAL, ANP BETWEEN THE ORIGINAL EXTREMES; 


THE AMOUNT OF ENERGy 
TRANSFERREP IS THE HEAT: 

MEAT I* THE ENERGY 
CHANGE ASSOCIATED 
WtTM A DIFFERENCE 
IN TEMPERATURE. 



09 




Internal Energy 



WHERE POES MEAT ENER&Y 
6-0? TO ANSWER THIS 
QUESTION, CONSIPER THIS 
COCONUT, WHICH REALLY 
STAN PS FOR ANy CHEMICAL 
SySTEM WITH A PEFINITE 
BOUNPARy BETWEEN ITSELF 
ANP ITS SURR0UNPIN6S. 


AT CLOSE RAN6E, THE COCONUT SEETHES WITH ENERGY. ALL ITS MOLECULES 
ARE JI66-LIN6 RANPOMLY, SO THEy HAVE KINETIC ENER6Y. THEy ALSO HAVE 
POTENTIAL ENER&y: ELECTRIC ATTRACTIONS ANP REPULSIONS ACCELERATE ANP 
PECELERATE PARTICLES, ANALOGOUS TO THE WAy GRAVITY WORKS ON A 
THROWN OBJECT. 



90 



A SYSTEM'S 

TEMPERATURE 

IS A MEASURE OF 
THE AVERAGE 
TRANSLATIONAL 
KINETIC ENERGY* 
OF ALL ITS 
PARTICLES, I.E., 
HOW FAST THEY 
FLY OR WIGGLE. 


THIS MAKES SENSE, GIVEN WHAT WE KNOW ABOUT TEMPERATURE. 
A HIGHER-T SYSTEM RAISES THE TEMPERATURE OF A LOWER-T 
SYSTEM BECAUSE HIGHER-ENERGY PARTICLES TRANSFER ENERGY 
TO LOWER-ENERGY ONES. 



THIS IS A BIT MORE COMPLICATE? THAN IT SOUNPS. IN GASES, T MEASURES HOW ENER¬ 
GETICALLY MOLECULES FLY AROUNP, BUT IN METALS, T ALSO INCLUDES THE ENERGY 
OF MOVING ELECTRONS... IN CRYSTALS, WIGGLING IONS HAVE P.E. AS WELL AS K.E., 
BECAUSE PARTICLES PULL AGAINST EACH OTHER... AN? MOLECULES COR PARTS OF 
MOLECULES; can ROTATE OR VIBRATE INTERNALLY. EVERY SUBSTANCE IS PlFFERENTf 



WHEN HEAT IS APPEP ANP INTERNAL ENERGY RISES, 
SOME OF THE APPEP ENERGY POES NOT CONTRIBUTE 
TO A RISE IN TEMPERATURE, BUT RATHER IS ABSORBEP 
AS P.E., ROTATION, OR INTERNAL VIBRATION. 


Different chemicals 
have different tem¬ 
perature responses 
to heat. 



translational energy is energy associated with particles moving through space, the 

ENERGY OF SPINNING ANp INTERNAL VIBRATION IS NOT INCLUDED. 


91 



Heat Capacity 

the HEAT £APA£ITY OF A substance 

IS THE EN£R£>y IMPUT REQUIRED TO 
RAISE ITS TEMPERATURE By 1°C. WE ON 
SPEAK OF HEAT 6APA£ITy PER 6-RAM 
fSPEOFl6 HEAT”) OR PER MOLE (“MOLAR 
HEAT aPA^ITT?. 





JAMES PRESCOTT JOULE 0010-1099) MEASURED THE HEAT 6APA6ITy OF WATER. 
HE ATTACHE? A FALLING WEIGHT TO A PAPPLE WHEEL IMMERSEP IN WATER. By 
MEASURING THE SLIGHT RISE IN TEMPERATURE OF THE WATER,* JOULE FOUNP 
THE WORK EQUIVALENT OF A TEMPERATURE 6HAN&E. RESULT-. 


WATER'S HEAT CAPACITY PER 6-RAM 

or 5PE£tFI£ HEAT is 



4.104 Joules/g °£ 

EXAMPLE: TO RAISE THE TEMPERA¬ 
TURE OF 5g OF WATER By 7°C 
REQUIRES AN APPEP ENER67 OF 

5 X 7 X 4.104 
= 146 JOULES. 


*yOV CAN RAISE TEMPERATURE BY POJN6. WORK ON AN OBJECT. FOR INSTANCE, WHEN YOU HAMMER 
A NAIL, THE NAIL HEAP WARMS UP. 



MERC, AT LAST, IS THE PRECISE RELATIONSHIP BETWEEN TEMPERATURE ANP HEAT; 

Heat change = 

Mass x AT x Specific heat 


AT? 



f CHANGE IN 
TEMPERATURE. 


FROM THAT SINGLE FORMULA ANP WATER'S SPECIFIC HEAT, WE CAN FlNP ALL OTHER 
SPECIFIC HEATS! LETS START WITH COPPER. IMMERSE 2 kq COPPER AT 25°C IN 5 kg WATER 
AT 30’C. LET THE TEMPERATURE STABILIZE. CHECK THE THERMOMETER. IT REAPS 19SVC. 
THE WATER BAREL y CHAN&EP TEMPERATURE, BUT THE COPPER REALLy HEATEP UP! 


5 kg AT BO” 


f 2kg 

1? AT 25” 




29.03Y 


29.0?*C 


THE TEMPERATURE 
CHANGES CAT) ARE 

at water --wr 

* 4 


WE CAN IMMEPIATELy CALCULATE WATER'S 
HEAT LOSS. CHEAT CHANGES ARE PENOTEP 
By THE LETTER qh 


I WATER 


= C5000g)C-0.17°OC4.10 J/g a O 
= -3553 Joules 

z'THE MINUS \ 
H -<I SI&N MEANS \ 
HA- 5 —■ THAT THE ] 
WL Bfi WATER OAVC / 
UP ENERC-y. / 


BUT THE WATER’S LOSS IS PREClSELy 
COPPER’S £AIN CASSUMIN6 NO HEAT 
LEAKS OUT OF THE VESSEL). THAT IS, 


'COPPER 


=■ 355? Joules. 


SINCE THERE WERE lOOOq OF COPPER, 
THE FORMULA SAyS; 

355? J » C2OOOgX4.03°)C Cu 

CC U = COPPER’S SPECIFIC HEAT) 

SOLVING FOR C Ai , 




355? J 

OOOO gX4.0? a ) 


» 0.37 J/g°C 


93 






AMAZIN6LY COPPER'S SPECIFIC HEAT IS LESS THAW ONE-TENTH THAT OF WATER. 
WATER CAW SOAK UP HEAT WITH LITTLE RISE IN TEMPERATURE, WHILE COPPER'S 
TEMPERATURE RISES ALMOST EFFORTLESSLY 



LI<?UIP WATER HAS MANY HyPRO&EN 
BONPS BETWEEN ITS MOLECULES (SEE 
CHAPTER V. THESE BONUS MAKE IT HARP 
TO 6ET A WATER MOLECULE MOVING 
APPEP HEAT LAR6£Ly SOES INTO THE P.E. 
ASSOCIATEP WITH THESE ATTRACTIONS. 


COPPER, ON THE OTHER HANP, HAS A 
“SEA” OF Hf&HLy MOBILE ELECTRONS. 
APPEP ENER6y SIMPLy MAKES THEM FLy 
AROUNP FASTER. THAT IS, HEAT ALMOST 
ALL 60ES INTO K.E., ANP TEMPERATURE 
RISES ACCORPIN&Ly. 


Pj 

) 


O C 


Vr' H. 

t ,'V //1 c o' 

MO / •' \ 

; 'fcy^-Ch' _v 

s' rZj ■ S’ <? [water" 


THIS EXPLAINS WHy 
WATER IS USEP AS 
A COOLANT IN 
MACHINERY FROM 
CAR ENGINES TO 
NUCLEAR REACTORS. 
THE HEAT TRANSFER 
FROM HOT METAL 
TO COOL WATER 
PROPS THE METAL’S 
TEMPERATURE PRA- 
MATICALLY WHILE 
RAISING WATER’S 
RELATfVELy LITTLE- 


SEE? I TOLP 
yOU I MEANT 
INFERNAL... i 


’k (/c/ 1 COPPER 



94 





MANy OTHER SPECIFIC HEATS CAN 

BE FOUND THE SAME WAY. IF WE 
REPLACE COPPER WITH IRON IN 

THE EXPERIMENT (SAME TEMPERA¬ 
TURES, same masses;, WE find 


NOW MEASURE IRON AOAINST 
ETHANOL, OR SRAIN ALCOHOL. 
ASSUME THE SAME MASSES 
AND A 5° TEMPERATURE 
DIFFERENCE AT THE START. 

AT w „ k * -O Wf 


• ' 0W 

AT,** » 4.79T 



FROM THE EXACT SAME COMPU¬ 
TATION AS BEFORE, WE FIND 


AND WE CALCULATE AS 
BEFORE-- 

C * OA 5 J/q °C 


£ * 2,4 l/a Q C 

^CTMAMOL ^ 

ALSO VERY LOW. 


CLOSER TO WATER. 


we can 

CONTINUE 

MEASURING 

ONE TMIN 6 - 

AOAINST 

ANOTHER 

UNTIL WE 

“BOOTSTRAP" 

A WHOLE 

TABLE OF 

SPECIFIC 

HEATS. 


SUBSTANCE 

SPECIFIC 

HEAT 

a/q°a 

MERCURy, Hq 


COPPER, Cu 


IRON, Fe 


c (oraphite; 

0.69 

SIMPLE MOLECULES 


ICE, W 2 0 (s) 

2.0 

WATER VAPOR, H 2 0 ( 9 ) 

2.1 

ANTIFREEZE, (CHjOHCH^H; 

2.4 

ETHANOL, (CH,CH 2 0H; 

2.4 

LIQUID WATER, UJXD 

4.2 

AMMONIA, NH,C0 

4.7 

COMPLEX MATERIALS 


BRASS 

0.30 

GRANITE 

0.79 

6 LASS 

0.0 

CONCRETE 

0.9 

WOOD 

1.0 


Note that antifreeze is a less ef¬ 
fective coolant than water, but 
it has the advantages of having 
a lower freezing point and being 
less corrosive to engine parts. 


V 









Calorimetry 

THE POINT OF ALL THESE 
PRELIMINARIES IS TO FlNP 

the HEAT £HAN6£$ OF 
CUmCAL REACTIONS: 

HOW MUCH ENERGY IS 
RELEASEP OR ABSORBEP AS 
HEAT WHEN A REACTION 
TAKES PLACE. WE ARE NOW 
IN A POSITION TO 
MEASURE THIS. 


THE METHOP IS SIMILAR TO THE WAV' WE FOUNP SPECIFIC HEATS= RUN THE REAC¬ 
TION IN A VESSEL OF KNOWN HEAT CAPACITY C ANP MEASURE THE CHANGE IN 
TEMPERATURE. SINCE THE VESSEL ABSORBS WHAT THE REACTION 6IVES OFF-OR 
VICE VERSA-THE HEAT CHANGE q OF THE REACTION IS -q VE ^ L - -CAT. 



MEASURE INITIAL 



RUN REACTION 



MEASURE FINAL. 



q = -CAT 

THE REACTION VESSEL ANP ITS SURROUNPIN6 PARAPHERNALIA TOGETHER ARE 
CALLEP A POMP £AtORlMETER. THE REACTION CHAMBER, OR “BOMB,” IS 
USUALLV IMMERSEP IN WATER, WHICH CAN BE STIRREP TO PJSTRIBUTE THE 
HEAT. A THERMOMETER COMPLETES THE APPARATUS. 


96 




Example 

COMBUSTION OF OCTANE C g W 10 , A COMPONENT OF GASOLINE: 

zc g u ig co + 2<?o 2 c^ —♦ uco 2 Cq) + ien 2 o(q) 

TO MEASURE THE HEAT GIVEN OFF, WE NEED A STRONG HEAVY BOMB TO WITH¬ 
STAND THE HIGH TEMPERATURE AND PRESSURE GENERATED. A THICK-WALLED 
STEEL CONTAINER OUGHT TO PO... LET’S SUPPOSE ITS HEAT CAPACITY IS 1 <5,000 
J/X. WE IMMERSE IT IN 2.5 L OF WATER, WHICH HAS A MASS OF 2500 < 3 . 


r 


THE WATER’S HEAT CAPACITY IS 
(25OOqX4.104J/q°Q = 10,460 J/X. 

SO THE CALORIMETER’S TOTAL 
HEAT CAPACITY IS 

10,460 + 1 5,000 = 25,460 J/X. 

SUPPOSE T,, THE INITIAL TEMPERA¬ 
TURE OF THE CALORIMETER, IS 25°. 



WE PROP ONE GRAM OF OCTANE INTO THE BOMB... IGNITE IT WITH A 
SPARK... IT BURNS... THE HEAT SPREADS THROUGHOUT THE CALORIMETER 
WE AGAIN CONSULT THE THERMOMETER, ANP FIND T 2 = 26.00°. THEN 


AT = T z - T, s 1.80* 

THE MAGIC FORMULA IS 

0 ' ~ ^aLORIMETER ^ 

WE PLUG IN ANP FIND 

q * -(.25,460 J/XX1.00X) = -47,000 J 

= - 47.0 kJ 

ANP WE CONCLUDE THAT OCTANE RELEASES 
47.0 IcJ/q OF HEAT WHEN BURNED. 



97 




Enthalpy 


THE BOMB CALORIMETER 
15 £REAT, WONPERFUL, 
FANTASTIC, BUT A BIT 
UNREALISTIC, BECAUSE 
THE REACTION VESSEL 
IS SEALEP. SOME REAC¬ 
TIONS IN THE BOMB 
MAy PROPUCE HJ6H 
PRESSURES, WHICH CAN 
AFFECT TEMPERATURE. 


IN THE BOMB CALORIMETER, THE 6ASES 
PO NO WORK, BECAUSE THE EXPLOSION 
IS CONFINEP IN A FlXEP VOLUME. ALL 
THE ENER&y IS RELEASEP AS HEAT. 


AE = q 

THEREFORE 
q = AW + WORK 
SO 

q > AW 


THE HEAT CHANSE IN THE BOMB IS GREATER 
THAN THAT IN THE OUTSIPE WORLP- 


IN THAT CASE, THE ENEROy CHANGE AE 

OF THE REACTION HAS TWO COMPONENTS, 

WORK anp HEAT: 



AE * AW + work 



PUSHING AIR HEAT 


§ 

OUT OF THE ^ance 


tn 

WAy COOLS 


Z 

m 

THE REACTION 



PROPUCTS.' 

x-x 

<N 

WORK 

mmn 

gg§|| 

> 

z 

<r> 

m 




AW HERE MEAW5 THE NEAT dHAW5E WHEM TWE 
REACT! Ok 15 RUN OITTTOOR5. 


FOR EXAMPLE. AN EXPLOSION IN THE OPEN AIR 6IVES 
OFF C-ASES THAT EXPANP RAPIPLY ANP PUSH THE 
SURROUNPIN6- AIR OUTWARP. IN OTHER WORPS, THE 
OASES PO WORK ON THE SURROUNPINOS. 



FROM NOW ON, WE TREAT REACTIONS AS IF 
THEy TAKE PLACE “OUTPOORS’’-MEANINO AT 
CONSTANT PRESSURE. IN THAT CASE, THE 
HEAT RELEASEP OR ABSORBSP IS £ALLEP 
THE ENTHALPY CHANGE, Anp 
WRITTEN A/y. 



90 






TO MEASURE ENTHALPY CHANCE, WE USE A CALORIMETER TMAT MAINTAINS 
CONSTANT PRESSURE. THEM THE PROCEPURE IS THE SAME AS WITH A BOMB 
CALORIMETER; MEASURE INITIAL AMP FINAL TEMPERATURES T, AMP T 2 , THEM 
MULTIPLY T 2 -T, TIMES THE HEAT CAPACITY OF THE CALORIMETER. 


Example 


EXPLOSION OF BLACK POWPER CHERE WE CIVE A MORE REALISTIC EQUATION THAN 
PREVIOUSLY): 

4KN0 ? (s) + 7C(s) + SCs) — 3C0 2 J + 3COT + 2N 2 | + K 2 C0,(s) + K 2 SCs) 

SUPPOSE OUR CALORIMETER HAS A KNOWN HEAT CAPACITY OF 337.6 kJ/X. WE 
START WITH SOOq OF POWPER. THE TEMPERATURE CHANCE AT IS FOUNP TO BE 
4.76°C, ANP WE COMPUTE 


AH = -cm .6 \a/°CX4.79 a O 
- -1614 kj 

FROM THIS WE CAN FtNP THE ENTHALPY CHANCE 
PER CRAM, AH/q, 

A U /gram = = -3.23 kj/q 


500 


Example 



HERE IS A REACTION THAT ABSORBS HEAT: 

CaCO ? Cs) CaOCs) + COJ 

WE START WITH THE CALORIMETER HOT ENOUCH TO PRIVE THE REACTION. AT THE 
ENP, THE CALORIMETER IS COOLER THAN AT THE BECINNINC. IF WE START WITH 
ONE MOLE OF CaCO v WE FINP THAT 


SO 


AT = -0.5?°C 

A!4 = - cm.6 kJ/ °C) C- 05VC ) 
= 179 kJ/mol 



REACTIONS THAT RELEASE HEAT CAW < 0) ARE CALIEP EXOTHERMIC- REACTIONS THAT 
ABSORB HEAT FROM THE SURROUNPINCS CAW > 0) ARE CALLEP ENPOTHERMIC. 


99 


Heats of Formation 


6 -REAT/ MOW WE CAN 
MEASURE AW FOR JUST 
ABOUT ANY REACTION' 
TOO BAP THERE ARE SO 
MANy REACTIONS... THIS 
COULP TAKE A WHILE... 
LUCKILy, INGENIOUS (OR 
LAzy; CHEMISTS HAVE 
THOUGHT UP A SHORT 
CUT'. INSTEAP OF 
MEASURING EMTHALPy 
CHANGES, WE CAN 
CALCULATE THEM. 



- 

THE BASIC CONCEPT IS CALLEP ENTHALPY OF FORMATION, WRITTEN AW f : 
THE ENTHALPy CHANGE THAT OCCURS WHEN A MOLE OF SUBSTANCE IS FORMEP 
FROM ITS CONSTITUENT ELEMENTS- FOR INSTANCE, WHEN A MOLE OF LIOUlP 
WATER IS FORMEP FROM HyPROC-EN ANP OXy<&EN, OUR CALORIMETER MEASURES 

H 2 (q) + j0 2 (q) -♦ H 2 0(l) A U f = AW = -205.0 kJ/mole 


EACH SUBSTANCE 
HAS A HEAT OF 
FORMATION, WHICH 
CAN EITHER BE 
MEASUREP OR 
INFERRED EVERy 
ELEMENT IN ITS 
MOST STABLE FORM 
(SUCH AS C, 0 2 OR 
S) HAS AW f = 0. 




6U85fAN($ A// fl kJ/mol 


COCtf 

-110.5 

C0 2 C<i) 


CaCOJs) 

-1207,6 | 

CaOCs) 

-635,0 

H jOCO 

-265,8 

H 2 0(9? 

-241,0 

SCs? 

0 

KN0 3 (s) 

-494.0 

KjCO^s) 

-1151.0 


-364.0 

W 

0 

W 

0 



1 00 





HOW PO WE USE HEATS OF FORMATION? HERE’S THE 
(PEA. IMAGINE ANY REACTION; REACTANTS —*PROPUCTS. 
LETS imagine IT AS TWO WCC ESSIVE REACTIONS: 
REACTANTS — CONSTITUENT ELEMENTS—»PROPUCTS. 



BREAKING THE REACTANTS 
INTO ELEMENTS HAS A 
HEAT CHANGE OF MINOS 
THE REACTANTS’ TOTAL 
ENTHALPHy OF FORMATION: 

AW, = -TOTAL AW f OF ALL 
REACTANTS. 

BUILPIN6 THE PROPUCTS HAS 
A HEAT CHANGE EQUAL TO 
THE PROPUCTS' COMBINEP 
ENTHALPHy OF FORMATION. 

AW a = TOTAL AW f OF ALL 
PROPUCTS. 


THE ENTHALPy CHANGE OF THE ENTIRE REACTION, THEN, IS THE TOTAL ENTHALPY 
CHANGE OF THE TWO INTERMEPIATE REACTIONS: 


AW * AW, + AW 2 

= A W f (PROPUCTS; - AW f CREACTANTS) 


THAT IS, IN ANY REACTION, AW IS 
SIMPLY THE PIFFERENCE BETWEEN 
THE ENTHALPIES OF FORMATION OF 
THE PROPUCTS ANP THE REACTANTS. 


L 



f T’S SO ) 
X^EASy'// 




THIS, By THE WAy, IS AN EXAMPLE OF A PRINCIPLE CALLEP HESS’S LAW: 
ENTHALPy CHANGE PEPENPS ONLy ON THE BESINNINS ANP ENP STATES, NOT 
ON ANYTHIN^ IN BETWEEN. IF A REACTION HAS INTERMEPIATE STAGES, THEN 
AW IS THE SUM OF THE INTERMEPIATE ENTHALPy CHAN&ES. 



101 




Examples 


LIMESTONE COOKS TO QUICKLIME: 

UCOp') -&* CaOCs) + C0 Z ] ' LH = ? 

WE MAKE AN ENER£y-BALAN££ TABLE, similar to the mass-balance tables of 

THE LAST CHAPTER. WE REAP THE HEATS OF FORMATION FROM THE TABLE ON P. WO 


REACTANT 

n = r\o. 
of moles 

AW f 

aAW f 

PROPU^T 

a 

AW f 

riAWf 

CaC0 3 

i 

-12(77.6 

-1207.6 

CaO 

D 

-655 

-655 





co 2 

1 

-595.0 

-595.0 

TOTAL 

-1207 M 


-1,(728.0 


THEN AW - AW f (PROPUCTS) - AW f (REACTANTS) 

= -1020.9 -(-12(77.6) » 1207.6 - 1020.9 
= 170.0 kJ FOR EACH MOLE OF CaO PROPUCEP. 

THE REACTION IS £NPOTMERMl£» AS WE HAVE SEEN. 



EXPLOSION OF NITRO&LyCERINE: 

AC^CmjJX) — 6NJ + 0 2 T + 12C0J + 1^M 2 0T 


REACTAMT n AW f nAW f PROPUCT ri AW f r\AW f 


4H/N0,), 

4 

-564 

-1456 


6 

(7 

0 






1 

0 

0 





H 2 0(g) 

10 

-241.0 

-2410.(7 





C0 2 (g) 

12 

-595.0 

-4725.6 

TOTAL 

-1456 


-7145.6 


AW - -7145.6 - (-1456) ^ -5607.6 kJ FOR FOUR MOLES OF NITROAL/CERINE. 
ONE MOLE OF NITRO RELEASES ONE-FOURTH AS MUCH: 

AW/mote ^ (-5607.6 )/4 = -1421.9 kJ/mol. 

ONE MOLE OF NITROSLyCERINE WEI6HS 227g, SO WE CAN ALSO CALCULATE AW/gram; 


AW/g » (-1421.9)7227 = -6.26 kJ/g. 




























MOTE THAT NITRO- \ 
OLYCERINE RELEASE!? \ 
TWICE AS MUCH HEAT J 
PER ORAM (b.U LJ) / 
AS BLACK POWPER / 
(3.23 kJ). 



COMBUSTION OF NATURAL OAS (METHANE, CH 4 ; 
CH 4 (g) + 20 2 (g)—C0 2 (g) + 2H 2 0(g) 


REACTANT 

n 


nA# f 

PROPUCT 

n 


r»AW f 

ch 4 

i 

-74.9 

-74.9 

C0 2 (g) 

t 

- 393.0 

-393.0 





H 2 0 (q ) 

2 

-241.6 

-403.S 

,—- 

TOTAL 

-74.9 


-077.4 


A// = -077.4 - (-74.9) = - 201.5 kj/mol, OR ABOUT -50.2 kJ/g 


WHEN 0 2 IS THE OXIPANT IN A REPOX REACTION (AS ABOVE;, THE ENTHALPY 
CHANOE IS CALLEP THE HEAT OF COM0l£TlON. COMBUSTION REACTIONS ARE 
HIGHLY EXOTHERMIC. BURNING HYPROOEN, FOR INSTANCE, RELEASES 20S kj/mol 
OR 14? kJ/g. ( = THE HEAT OF FORMATION OF WATER. SEE P. IPP; SOME OTHER 
HEATS OF COMBUSTION, IN kT PER ORAM OF FUEL*. 



HYPROOEN 

149 

NATURAL OAS (CH 4 ) 

SP 

OASOLINE 

48 

CRUPE OIL 

43 

COAL 

29 

PAPER 

2 <? 

PRIEP BIOMASS 

IS 

AIR-PRIEP WOOP 

15 















IN THIS CHAPTER WEVE SEEN HEAT GHANGES IN TWO DIFFERENT CONTEXTS: 
FIRST, ASSOGIATEP WITH TEMPERATURE (CHANGES, ANP SEGONP, ASSOGIATEP WITH 
REACTIONS. IN THE NEXT CHAPTER, WE FlNP HEAT IN ANOTHER, SURPRISING 
PLAGE-- CHANGES OF STATE- 



YOU MEAN, 
LIKE GOING 
TO OREGON? 


AllV V' * xl*u 




THAT IS, WHEN A SUBSTANCE CHANGES FROM A SOUP STATE TO UQUlP COR 
UQUIP TO GAS, OR GAS TO SOUP, ETC,), HEAT IS APPEP OR TAKEN AWAY—ANP 
THIS HAPPENS WITH NO GHANGE IN TEMPERATURE. AT TIMES, IN OTHER WORPS, 
HEAT GAN GHANGE STRUCTURE RATHER THAN TEMPERATURE. 


f HOW INEFFABLY N 
MySTERIOUS... WHERE 
POES THE ENERGy GO? 






Chapter 6 

Matter in a State 

UNPER ORPINARY ^OWPITIONS-OUTSIPE OF STARS, SAY-MATTER £OMES IN 
THREE STATES: SOUP, LIQUIP, ANP SAS. 





WHAT HOLDS SOUPS AMP LIQUIPS 
TOGETHER? THE ANSWER LIES WITH 
INTERMODULAR FORCED 
ClMFs) WITH IM THE SUBSTANCE. 
THESE ARE ATTRACTIONS BETWEEN 
MOLECULES CAS OPPOSE? TO THE 
BONPS WITHIN A MOLECULES 



/ \ 

ONE IMF WE HAVE ALREADY ENCOUNTERED IS THE HYPRO^EN BONP. IN 
WATER MOLECULES, ELECTRONS STAY CLOSER TO THE OXY&EN ATOM, SO THE 
HYPRO&EN ATOMS EFFECTIVELY CARRY A POSITIVE CHARGE- THIS ATTRACTS 
THEM TO THE NEGATIVE POLE OF ANOTHER WATER MOLECULE. 



BECAUSE OF ITS TWO ELECTRIC POLES, A WATER MOLECULE IS CALLED A PIPOL£. 
MANY OTHER MOLECULES ARE DIPOLES, TOO, AND THEY ATTRACT EACH OTHER 
END TO CHARGED END. DIPOLES MAY ALSO ATTRACT IONS- 



PJPOt-E~PJPOL£ JON-PJPOLk ATTRACTION 

ATTRACTION 


v_ J 




NONPOLAR MOLECULES CAN BECOME PI POLES. FOR EXAMPLE, WHEN AN ION NEARS 
A MOLECULE, THE ION’S CHARGE CAN PUSH OR PULL THE MOLECULE’S ELECTRONS 
TOWARP ONE ENP. THE MOLECULE BECOMES AN INPUCEP PIFOtC, ANP ONE 
ENP IS ATTRACTEP TO THE ION. A PIPOLE CAN INPUCE ANOTHER PIPOLE, TOO. 



EVEN THE 6HOSTLY FLIGHT OF ELECTRONS WITH1M AN ATOM OR MOLECULE 
CAN MAKE IT AN “INSTANTANEOUS” PI POLE-WHICH CAN THEN INPUCE A NEARBY 
ATOM OR MOLECULE TO BECOME A PIPOLE, ETC. THE RESULTING RIPPLIN6 
ATTRACTION IS CALLEP THE LONPON PI$PER$lON FORCE- 



A TEMPORARY CHARGE IMBALANCE SETS OFF A RIPPLE OF PIPOLE-PIPOLE ATTRACTIONS- 


ALTHOUGH THEY ARE CALLEP INTER- 
MOLECULAR FORCES, THESE ATTRACTIONS 
PO NOT OPERATE ON MOLECULES ONLY. 
NOBLE 6AS ATOMS, FOR INSTANCE, FEEL 
THE LONPON PlSPERSiON FORCE- 



FROM NOW ON, WE’LL BE A LITTLE LOOSE 
WITH LANC-UASE ANP SOMETIMES REFER 
TO IMF* AS BONPS- BONPS OR IMF*: 
THEY’RE ALL ELECTRIC ATTRACTIONS BE¬ 
TWEEN PARTICLES' 



1P7 




THIS TABLE SUMMARIZES THE STRENGTHS Of DIFFERENT ATTRACTIVE 
FORCES. THE 5TREM6TH OF A BONP MEANS THE ENERGY REQUIRED 
TO BREAK IT. 


Strong attractions 


STRENGTH 

IONIC 300-1000 kJ/mol 

ION-ION ATTRACTION 

METALLIC 30-1000 IcT/mol 

ELECTRON 5MARIN6 
AMON& METAL IONS 

COVALEMT 300-1000 kJ/mol 

ELECTRON SHARING 

Moderate attractions 

HyP*06EN BONP* 20-AO kJ/mol 

AM EXPO*£P PROTOM 
IM OMe MOLECULE 
ATTRACTS A ME6AT!Vay 
CHAR&EP ATOM JN A 
NEARBV MOLECULE 

fON-PJPOLE 10- 20 kj/mot 


Weak attractions 


PIPOLE-PIPOLE 

ION-INPUCEP PIPOLE 

PIPOLE-IWPUCEP PIPOLE 

INSTANTANEOUS PIPOLE- 
INPUCEP PIPOLE (pispersion; 


1 - 5 kJ/mol 
1 - 3 kJ/mot 
0.05 - 2 kJ/mol 
0.05 - 2 kJ/mol 


NOTE; PISPERSION FORCES 
ARE GREATER BETWEEN 
LAR6ER ATOMS, WHICH 
HAVE MORE ELECTRONS TO 
PUSH AROUNP ANP WHERE 
ELECTRONS ARE FARTHER 
FROM THE NUCLEUS ANP 
SO MORE EASILY PUSHEP. 



100 



AS EVERYONE KNOWS WHO HAS EVER SEEN ICE MELT, TEMPERATURE AFFE6T5 
STATE- RAISE THE TEMPERATURE OF ANYTHING HI6-H ENOUGH, ANP IT BECOMES A 6AS. 
HOW HI6-H PEPENPS ON THE BONP ANP IMF STRENGTHS WITHIN THE SUBSTANCE. 


WOWI A 
WATCHEP POT 
REALLY POES 
BOIL' 


% 


a> 


YOU’LL BE 
FAMOUS., 


O 


|OO(T)O0 


SUBSTANCES WITH WEAK 
IMF* CAN BE SOUP OR 
LIQUlP ONLY AT VERY LOW 
TEMPERATURES, WHEN PAR¬ 
TICLES MOVE SLU66ISHLY. 



AS TEMPERATURE RISES, 
MOLECULAR MOVEMENT 
STRAINS IMF*. IF THE 
FORCES ARE WEAK, THE 
SUBSTANCE MUST BECOME 
LIOUIP OR GASEOUS. 



BY CONTRAST, STRONGLY 
BONPEP SUBSTANCES CAN 
REMAIN SOUP EVEN AT 
THOUSANPS OF PE&REES 
CELSIUS. 



IN OTHER WORPS, 
SUBSTANCES WITH 
WEAK IMF* MELT ANP 
BOIL AT LOWER TEM¬ 
PERATURES, WHILE 
THOSE WITH STRONG 
BONPS MELT ANP BOIL 
AT HIGHER TEMPERA¬ 
TURES. WATER, WITH 
ITS HYPROSEN BONPS, 
IS SOMEWHERE IN 
BETWEEN. 


SUBSTANCE 

FORCG 

BOM 17 
5TREM6TM 
CkJ/moD 

MGLVH6 

POINT 

CO 

BOJUN6 

POINT 

CO 

A r 

PJ$PER$ION 

e 

-199 

-196 

NH, 

kypRO&EN 

36 

-70 

-33 

H 2 0 

kyt?RO£EM 

23 

0 

1 00 

Hcs 

METALLIC 

69 

-39 

366 

A! 

METALLIC 

324 

660 

2461 

Fe 

METALLIC 

406 

1636 

2160 

Nad 

tom 

640 

901 

1413 

MqO 

tom 

1000 

2900 

3600 


COVALENT 

460 

1420 

2366 

C CPIAMONP) 

COV ALEUT 

713 

3660 

4099 


109 





THE SIMPLEST STATE OF MATTER HAS (ALMOST) WO IMFS AT ALL- 


Gases, Real and Ideal 


GAS PARTICLES ZOOM 
AROUNP PREELy, OR 
WEARLY SO. WHEW THEy 
PO BUMP I WTO EACH 
OTHER, THEy FEEL AW 
IMF, SO THEIR COL¬ 
LISION* ARE A BIT 
“STICKy” O.E., SOME K.E. 
IS LOST IN OVERCOMING 

the attraction;. 



FOR THEORETICAL PURPOSES, CHEMISTS IGNORE THIS MINOR COMPLICATION AMP THINK 
ABOUT AN |p£AL 6A6. IN AN I PEAL GAS, ALL PARTICLES ARE IPENTICAL, THEy ZOOM 
AROUNP FREELy, ANP ALL COLLISIONS ARE PERFECTLy BOUNCE OR ELASTIC—THAT 



ONE CAN PISCUSS CERTAIN PROPERTIES OF AN IPEAL GAS: 


n THE NUMBER OF MOLES, A 
I! MOLE BEING 6.02 X 10 2? 
PARTICLES 

yf THE VOLUME 


f PRESSURE? WHAT’S \ 
PRESSURE? COME ON? I o 
TELL ME? RIGHT WOW? ) n 
v_ HURRy UP? / Q 


T THE TEMPERATURE IN 
PEGREES KELVIN 


THE PRESSURE 


- ft 


^ rw&J 


up 





PRESSURE IS / 
PEFINEP AS 
fORCG PER 
UNIT OF AREA. 

A FORCE APPLIEP 
TO A SMALL- AREA 
CAN HAVE MORE 
EFFECT THAN A 
FORCE SPREAP 
OVER A LARGE 
AREA. THAT’S WHy 
you SIT ON A 
STOOL INSTEAP 
OF A NEEPLE? 
SAME FORCE 
(YOUR weight;, 
PIFFERENT AREA. 


•- -3 


Pressure = F _ ot>ce 

Area 


GAS HAS PRESSURE 
BECAUSE ITS PARTI¬ 
CLES BUMP INTO 
THINGS. , 

r^n r~\ rfci 


jy * r 


SINCE POUBLING AN 
AREA POUBLES THE 
NUMBER OF COLLISIONS 
ANP SO POUBLES 
THE FORCE, FORCE 
ANP AREA GO UP 
TOGETHER, SO THE 
PRESSURE IS CON¬ 
STANT THROUGHOUT 
THE GAS. 


THE AIR AROUNP US EXERTS ATMOSPHERIC PRESSURE. ONE ATMOSPHERE 
0 atm; IS THIS PRESSURE CON AVERAGE} AT SEA LEVEL. IN TERMS OF METRIC 
UNITS: 

t atm * 101,329 NEWTONS/m 2 
* 10.1325 NEWTONS/cm 2 

ATMOSPHERIC PRESSURE IS HU6E/ 

WE PON’T FEEL IT BECAUSE IT PUSHES 
FROM ALL PIRECTIONS, BUT RECALL 
GUERICKE'S EXPERIMENT WITH HORSES 
TO APPRECIATE ITS TRUE MAGNITUPE. 








Gas Laws 


MOT SURPRISINGLY, n, T, V, ANP ? ARC ALL RELATE?. FOR INSTANCE, YOU MIGHT 
EXPERT THAT MORE PARTICLES WOULP OCCVPY A GREATER VOLUME, ALL ELSE 
BEING EQUAL- AMP SO THEy P O! IM FACT, IT’S A LAW, THE FIRST OF THREE 
GAS LAWS, WHO WE LIST IM ALPHABETICAL ORPER. 


AVOSAPRO’4 LAW; IF 

T AMP P ARE FlXEP, THEM 
VOLUME IS PROPORTIONAL 
TO THE NUMBER OF MOLES. 



OTHERWISE, PRESSURE 
WOULP CHANGE, 
woulpnt rr? 


. w 


THIS IMPLIES THAT A SET VOLUME OF GAS (AT FlXEP T ANP ?) 
ALWAYS HAS THE SAME NUMBER OF MOLECULES-no matter 
WHAT WHAT GAS IT IS' THIS FACT ENABLE? NINETEENTH-CENTURY 
CHEMISTS TO FINP ATOMIC WEIGHTS FOR THE FIRST TIME. 


BOYLG’t LAW: IF n AMP T 

ARE FlXEP, THEM VOLUME IS 
INVERSELY PROPORTIONAL TO 
PRESSURE. 

p,v, -- P 2 V 2 


0 O 




/ //XW • ft % // 


IN A LARGER VOLUME, 
FEWER PARTICLES MfT 
A UNIT OF AREA- 


THAN IN A SMALLER 
VOLUME, 


CHARLES LAW: with a ami? P 

FIXER, VOLUME 1$ PROPORTIONAL 
TO TEMPERATURE. 

V, v 2 


nTT” 


IF T RISES- 



m 


MORE-ENERGETIC PARTI¬ 
CLES PUSH UP THE PISTON, 



ALU THESE LAWS CAN BE ROLLEP INTO A SINGLE EQUATION THAT COMBINES 
THE RELATIONSHIP AMON& ALL FOUR VARIABLES. IT’S CALLEP THE I PEAL 6A$ 
LAW, ANP IT 60ES 

/'TT') ( A CONSTANT ' 
( K r / l OF NATURE. . 



HOLP ANy TWO VARIABLES FIXEP, ANP yOU SEE THE 
RELATIONSHIP BETWEEN THE OTHER TWO AS 6 IVEN 
IN THE A, B, C LAWS ON THE PREVIOUS PA 6 E. 


R CAN BE FOUNP AS FOLLOWS; FIRST, EXPERIMENTALLy PETERMINE THE VOLUME 
OF ONE MOLE OF 6 AS CANy 6 -AS, By AV06APR0J). AT OX C- 27T\0 ANP 1 ATM, 
IT TURNS OUT that ONE MOLE OF OCCU? IE$ Z2.4 LITERS. SO; 


n = 1 mol 
T * 17? K 
P - 1 atm 

V = 22.4 L. ^ 

PLU6 INTO THE 6AS UW EQUATION; 

0 atm) (22 .4 L) = (1 mol)R(27?°lO 
SO 

R = (22.4/27?) atm-L/moHC 
= 0.091 atm-L/mol °K 


THE CONPITIONS 

T = 0°C ANP 
P = 1 atm 

ARE KNOWN AS 5TANPARP TEM¬ 
PERATURE ANP PRESSURE (97?). 



WHAT A 
SAS/ 



11 ? 




Example: 

WHAT VOLUME OF 6AS IS RELEASE? By THE EXPLOSION OF ONE &RAM OF 
BLACK POWPER? 

A KNO ? (s) + 7C& + SCs) — 3COJ + 3CO] + 2N 2 f +K 2 C0 3 (s) + K 2 S(s) 

\ / ^ 

3 + ? + 2 * 0 mol 6AS 


THE MOLAR WEIGHT OF THE LEFT 
SI PE IS 520 <3, WHICH PROPUCES 
9 mol 6AS. SO ONE 6-RAM OF 
POWPER PROPUCES 

(1/510) (9) = 0.015 mol 6-AS. 


SO a - 0.0 15. P = 1 atm, ANP 
EXPERIMENT SHOWS THAT THE 
TEMPERATURE T IS ABOUT 2250 < ’K. 



SOLVING FOR VOLUME, 

v - "51 

P 

(0.015 modCO. 091 atm-L/monO (2250°) 
1 atm 



A 6-RAM OF POWPER, WE MEASURE, OCCUPIES A TINy VOLUME, ABOUT 0.6 mL. 


THE EVOLVEP 6AS EXPANPS TO 
(2000?/ (0.6) = 3,500 TIMES 
THAT VOLUME' IF WE WANTEP TO 
CONFINE THE SAS IN A LITTLE 
PACKAGE 1 mL (= .001 L) IN 
VOLUME, IT WOULP BUILP UP A 
PRESSURE OF- 



(0.015X0-091X1150) 

( 0 . 001 ) 


OR ABOUT 2900 atm. 



114 




Liquids 

BECAUSE OF THEIR IMF*, LIQUID HAVE COM PLICATEP BEHAVIOR. THERE ARE MO 
“IPEAL LIQUIPS." 



LIQUIPS BEHAVE AS IF THEY HAVE A 
SKIN. ATTRACTION AMON6 SURFACE 

molecules-$URFACE TEW 5IOM- 

KNITS THEM TOGETHER MORE TIGHTLY 
THAN INTERIOR MOLECULES. THAT EX¬ 
PLAINS WHY BU6S CAN WALK ON WATER 



O 

.o ° 


r ANP WHY 
LIQUIPS FORM 
SPHERICAL 
PROPLETS! 


LIQUIPS EXPANP WHEN HEATEP: AS MOLECULES 
MOVE FASTER, THEY 6-ET FARTHER APART. THIS 
MAKES THERMOMETERS POSSIBLE: THE LIQUIP- 
MERCURY OR WHATEVER—EXPAN PS UP THE TUBE 
WHEN WARMEP, ANP SHRINKS WHEN COOLEP. 


° ° 

° y 

o o 

o o//A 


A 0 ° 

a o 

o 


V 


ex' 





Evaporation and Condensation 


IN MOST LIQUIDS, MOLECULAR 
MOVEMENT CAN OVERCOME 
COHESIVE FORCES. IN THAT 
CASE, SOME MOLECULES BREAK 
THROUGH THE SURFACE AND 
EVAPORATE. CONVERSELY, 

LESS-ENERGETIC VAPOR 
MOLECULES MAY COLLECT INTO 
LIQUID, OR £ONPEN$E. 



WHEN A MOLECULE GOES GASEOUS, ENERGY MUST BE ABSORBED FROM THE 
SURROUNDINGS TO BREAK THE ATTRACTIVE FORCES ("BONDS, IMF$; THAT EXIST 
WITHIN THE LIQUID. EVAPORATION 1$ ENP0THERMI6 


liquid—► gas AH>0 V % 


I AM SO 
JEALOUS... 


IN OTHER WORDS, GAS IS A MORE 
ENERGETIC 5TATE OF MATTER 

THAN LIQUID. 


£* A ‘ 







c^a'o' - 


FOR EXAMPLE, WATER’S HEAT OF VAPORIZATION (AT 1 atm, V?X) IS 44 kJ/mol, 
THAT IS THE ENTHALPY CHANGE OF THE ‘REACTION” H 2 0(l> — H 2 0(g). 


THIS IS WHY 
PERSPIRATION 
WORKS. EVAPO¬ 
RATING SWEAT 
DRAWS HEAT 
FROM YOUR 
BODY. 



116 


A BRILLIANTLY DIMPLE APPLiaTION 
OF THIS 44 kJ/mol 1$ TME £OOL!N6 
POT OF NIGERIAN POTTER 

mohammap pah appa. 



one cim pot ditd mm 

ANOTHER, WITH A LAYER OF WET 
DANP IN BETWEEN. THE OUTER 
POT 1$ UN&LAZEP ANP POROUS. 



WATER 

VAPOR 

ANP 

HEAT 


IN A PRY ENVIRONMENT, THE 
WATER IN THE DANP LAYER 
EVAPORATED ANP PADDED OUT 
THROUGH PORED IN THE OUTER 
POT. IN THE PRC^EDD, IT PRAWD 
HEAT FROM THE APPARATUS 


THE TEMPERATURE INDIPE £AN 
FALL AD FAR AD 14 °C (• 25°f) 
BELOW THAT OF THE OUTDIPE- 
A LIFEDAVER IN PEDERT ^UN¬ 
TRIED WHERE MODT PEOPLE 
CANNOT AFFORP A FRIP6E. 



117 








NOW IMAGINE A LIQUIP IN A CLOSEP 
CONTAINER AT CONSTANT TEMPERA¬ 
TURE. AS LI QUIP EVAPORATES, VAPOR 
BUI UPS UP, ANP SOON SOME OF - 
THIS VAPOR BEGINS TO CONPENSG. 



AT FIRST, EVAPORATION OUTPACES (COMPENSATION, BUT EVENTUALLY COMPEN¬ 
SATION MAY CATCH UP. WHEN THE TWO PROCESSES EXACTLy BALANCE, THERE 
IS NO NET CHANGE IN THE AMOUNT OF LIQUIP OR 6AS. THE TWO STATES ARE 
SAIP TO BE IN EQUILIBRIUM, ANP WE WRITE 


liquid 


NOTHING APPEARS 
TO BE HAPPENING, 
BUT ACTUALLy TWO 
THINGS ARE/ 


vapor 





EQUAL RATES 


THE EXTRA PRESSURE PUE TO 
VAPOR ALONE IS CALLEP ITS 

PARTIAL PRESSURE/ AS 

VAPOR BUILPS UP, ITS 
PARTIAL PRESSURE RISES 
STEAPILy CBISSER rv, SAME V 
ANP TO UNTIL EQUILIBRIUM. 
AT EQUILIBRIUM, THIS PARTIAL 
PRESSURE IS CALLEP THE 

vapor 

pressure. 

ITS THE PRESSURE THE 
VAPOR ‘‘WANTS" TO ATTAIN. 


VAPOR PRESSURE (P v ) RISES WITH TEMPERATURE, 
SINCE MORE-A6ITATEP MOLECULES HAVE A GREATER 
“NEEP” TO VAPORIZE. 


WOW/ TALK 
ABOUT PESIRE! 



VAPOR PRESSURE 

OF WATER 

T CO 

p v catm; 

0 

P.PPA 

10 

O.OIZ 

AO 

O.OTZ 

60 

P.197 

90 

P.4A7 

90 

P.A92 

WO 

1.PP 

100 

15.34 

ZOO 

94.0 


“THE TOTAL PRESSURE OF A MIXTURE OF &ASES IS THE SUM OF ALL THEIR PARTIAL PRESSURES. 









P v IS THE PRESSURE AT 
WHICH VAPOR “WANTS" 
TO STABILIZE- BUT 
WHAT IF NO MATTER 
HOW MUCH VAPOR THE 
LIQUIP SPEWS, ITS 
PRESSURE NEVER 
REACHES P y ? IN THAT 
CASE, VAPORIZATION 
60ES UNCHECKED ANP 
THE LIQUIP £0IL$. 




119 











THE TEMPERATURE AT WHICH 
A LIQUIP BOILS IS CALLEP ITS 

boiling point 

BOILIN& POINT PEPENPS ON 
EXTERNAL PRESSURE. 





AT SEA LEVEL (PRESSURE * 1 ATM;, 
WATER BOILS AT 100° C, BUT AT HI&H 
ALTITUPE, WHERE AIR IS THIN, SOILING 
POINT (AN PROP BELOW 05°. IN THE 
VACUUM OF SPACE, WATER BOILS AT 
ANV TEMPERATURE. 



EXTERNAL PRESSURE, By THE WAY, 

CAN INCLUPE LIQUIP PRESSURE AS 
WELL AS 6AS PRESSURE. IN THE PEEP 
OCEAN (PRESSURE VERY W<?W) WATER 
NEAR VOLCANIC VENTS CAN REMAIN 
LIQUIP ABOVE B5C>°C. 


I’M 
COOKEP.' 




WE SUMMARIZE ALL THIS WITH A LI<?UIP-£AS MINI-PIA6-RAM. THE HORIZONTAL 
AXIS IS TEMPERATURE; THE VERTICAL AXIS IS PRESSURE; ANP AT EAZH PAIR OF 
VALUES (T,?) WE SEE WHETHER A SUBSTANCE IS LIQUlP OR OAS. 


THE ZURVE BETWEEN THEM JNPIZATES 
THE BOILING POINT FOR ANy PRESSURE. 



_ii 

T-► 


NOTE THAT PHASE TRANSITIONS ZAN RE¬ 
SULT FROM ZHAN6IN6 PRESSURE ALONE, OR 
TEMPERATURE ALONE, OR A ZOMBINATION. 



T-► 


THE ZURVE HAS ITS LIMITS. EVERy LIpUlP HAS A ZHARAZTERISTIZ CRITICAL TEM¬ 
PERATURE, THE HIGHEST AT WHIZH THE LIQUIP STATE ZAN EXIST. ABOVE THE 
ZRITlZAL TEMPERATURE, NO AMOUNT OF PRESSURE ZAN STOP THE LIQUIP FROM 
BOILING AWAy. 



121 










Melting Solids 

IN THE OPEN AIR, MANy LIQUJPS SIMPLy EVAPORATE AWAy. SINCE THE VAPOR ESCAPES, 
IT BUlLPS UP NO SIGNIFICANT PRESSURE ON THE SURFACE, ANP EVAPORATION 
CONTINUES INPEFlNITELy. 







VAV‘X'. : - 

PARTIAL 

PRESSURE 

/ M- . • 

MOLE¬ 

CULE* 


-TS 

P v AT * 

♦ * % 

KEEP 

i | 

6URPACS, 
l\K <P V 

WITHER 

UP, *o». 

• • ■ 

• ,* < ’• 1 

L£AVfN6. 

x » 

;__ 

: >s^7 




<— y 


IN SOUPS, gy CONTRAST, VERy FEW PARTICLES HAVE ENOUGH ENERGy TO ESCAPE. 
VAPOR PRESSURE IS LOW—THOUGH NOT SO LOW WE CAN’T SMELL MANy SOLIPS. 
IN SOME CASES, VAPOR PRESSURE IS VIRTUALLy NIL- PIAMONPS ARE FOREVER/ 



AS WE ALL KNOW, SOLIPS 
MELT*, anp thev po so 

AT A SET TEMPERATURE, 
THE MELTING POINT, 
WHICH VARIES FROM SOLIP 
TO SOLIP. 



AT THIS TEMPERATURE, ANy APPEP HEAT IS ENTIRELy 
CONSUMEP IN BREAKING BONPS UNTIL THE SOLIP IS 
comp LETELy meltep. MELTIN6, LIKE EVAPORA¬ 
TION, 15 ENPOTMERMI£ 

SOUP —» LIOUIP AW > 0 

THIS ENTHALPHy CHANGE IS CALLEP THE HEAT OF 
FUSION. FOR ICE AT STP, IT’S 6.01 HJ/wiol. 



*U*UALiy. SOME OF THEM SUBLIME, or go straight to the GhG pha$e. more oh THAT SHORTLY. 


122 









EXTERNAL- PRESSURE AFFECTS MELTING 
POINT- IN THIS SOLIP-UQUIP MINI-PIAGRAM 
WITH P ANP T AXES, THE CURVE SHOWS 
THE MELTING POINT FOR EACH VALUE 
OF P. 



T -► 


THE EFFECT IS LESS PRAMATIC THAN WITH 
BOILING POINT, HOWEVER, SO THE MELTING 
CURVE IS USUALLY PRETTY STEEP. 



BIG CHANGE IN P 
PROPUCEG REUT(VEl.y 
5MALL C HANGE IN 
MELTING POINT. 


IN A FEW WEIRP MATERIALS, APPEP 
PRESSURE ACTUALLY PECREASES 
MELTING POINT. WATER IS ONE SUCH- 



T 


THAT’S BECAUSE WATER EXPANP6 WHEN 
rr FREEZES. THE CRYSTALLINE STRUCTURE 
OF ICE IS UNUSUALLY SPACIOUS. 


rr—cy 

SH 

V ..A. ih A 

LIOUIP H 2 0 

ICE 


PRESSING ON AN ICE CUBE 
PUTS STRAIN ON THE BONPS 
ANP PRIVES THE MOLECULES 
INTO A TIGHTER BUT MORE 
RANPOM CONFIGURATION, 
ANP THE ICE MELTS AT THE 
POINT OF PRESSURE. 



SO, UNLIKE MOST SOLIPS, ICE FLOATS ON ITS LIQUIP 
FORM... THE EXPANSION OF FREEZING WATER CAN CRACK 
ROCKS... ANP THIS OPP FEATURE HAS A PROFOUNP 
IMPACT ON THE WORLP AROUNP US- 



ICE-SKATING AS IT WOULP BE IF WATER FROZE LIKE 
A NORMAL SUBSTANCE. 


















Phase Diagrams 

PUT OUR MINI-PIA&RAMS TOGETHER AMU TMEY SHOW A COMPLETE PICTURE OF 
THE THREE STATES OF MATTER IM- TERMS OF T ANP P. THE SOLIP-LIQUIP CURVE 
MEETS THE LIQUIP-6AS CURVE AT A TRIPLE POINT WHERE ALU THREE PHASES 
ARE IM EQUILIBRIUM. 


t 


CRITICAL POIMT 



T 


. 

MOTE THAT THERE ARE ALSO COMPITIOMS WHEM A SOUP CAM CHAN6E PIRECTLy 
INTO A 6AS, A PROCESS CALLEP SUBLIMATION . THE REVERSE PROCESS, 

6AS —» SOUP, IS PEPOSITION. THE BEST-KNOWN EXAMPLE AT NORMAL PRES¬ 
SURE IS C0 2 , “PRy ICE,” THE STUFF USEP IM THEATRICAL SMOKE MACHINES. 



124 









A COUPLE OF OTHER PHASE PIAGRAMS SHOW SOME MORE SUBTLE AMP UNUSUAL 
FEATURES OF MATTER- HERE IS IARBON. 



TEMPERATURE, ’K 



CARBON HAS THREE SOUP FORMS, WITH PlFFERENT CRYSTALLINE STRUCTURES'- GRAPH¬ 
ITE, FOUNP IN COAL ANP PENCIL LEAPS, PIAMONP, WHICH IS FORMEP ONLY UNPER HIGH- 
PRESSURE CONPITIONS, ANP METALLIC, WHICH EXISTS ONLY AT EXTREMELY HIGH PRESSURE 
NOTE HOW THE MELTING CURVE SLOPES PlFFERENTLY FOR EACH TYPE OF CRYSTAL 



HELIUM, LIGHTEST OF 
THE NOBLE GASES, HAS 
EXTREMELY WEAK IMF*. 
AT 1 ATM, ITS BOILING 
POINT IS JUST OVER 4°K, 
OR -2G9°C. THAT’S 
REALLY COlVUl 



BELOW THAT TEMPERATURE IT IS A LIPUIP... ANP BELOW 2.17‘K-IT IS ANOTHER KINP OF 
LIOUIP' THIS HELIUM II IS A “SUPERFLUIP” WrTM WEIRP PROPERTIES. IT FLOWS WITHOUT 
VISCOSITY (GOOPINBSSA- IT WILL LEAK OUT THE TINIEST PORE- IT WILL EVEN CLIMB THE 

CONTAINER WALLS? SEE http://cryowwwcbLeT.95fc.na5a.qov/tntroducti13n/liqutiJ hcliuTn.html 

FOR PETAILS. HELIUM CAN ALSO BE SOLIP, BUT ONLY AT PRESSURES ABOVE 25 ATM. 


125 







Heating Curves 

FINALLY, LETS RETURN TO THE HEATS OF FUSION ANP EVAPORATION, ANP SEE HOW 
THEy PUy OUT WHEN WE HEAT A BLOCK OF ICE UNTIL IT MELTS ANP THEN BOILS. 



LET'S USE 
MICROWAVES 
TO HEAT 
THE WATER 
UNIFORMLY 



LETS SUPPOSE THE ICE’S INITIAL TEM¬ 
PERATURE IS -S°C. AS WE APP HEAT, 
TEMPERATURE RISES TOWARP OX. 



AT THE MELTING POINT, TEMPERATURE 
STALLS AT 0\ EVEN THOUGH WE KEEP 
APPING HEAT. 



ALL THE APPEP HEAT GOES INTO BREAK¬ 
ING BONPS WITHIN THE ICE CRySTAL. 


ONLy WHEN THE ICE IS FULLy MELTEP 
POES TEMPERATURE RISE AGAIN. 





' / I W\A^ 


AT THE BOILING POINT, TEMPERATURE 
AGAIN STALLS, AS HEAT IS TAKEN UP By 
PHASE CHANGE ALONE. 


ONCE THE WATER IS FULLy VAPORIZEP, 
THE STEAM’S TEMPERATURE RISES. 






_____ _____ —s, 

THAT SIX-PANEL COHAC STRIP TRANSLATES INTO THIS HEATIN6 C \)RVE 
THAT PLOTS TEMPERATURE AOAINST APPEP HEAT. T STOPS RISING PURIN6. PHASE 
TRANSITIONS. 



V__ j 


THE SPECIFIC HEAT OF WATER. 
RECALL. IS AROUNP 4.10 J/q °C . 
SO TO RAISE THE TEMPERATURE 
OF ONE S-RAM OF LIQUIP WATER 
gy 100° REQUIRES AN APPITION 
OF ABOUT 

(4.18 Z/°CK\00°O 
= 410 Joules 


BY CONTRAST, AT 100°C THE HEAT 
OF VAPORIZATION OF WATER 1$ 
ABOUT 41 KILOJOULES PER MOLE- 
SIN(E A MOLE OF WATER WEIGHS 
10 6RAMS, THIS IS 


41 kJ/mol 
10 q/mol 


» 2.28 kJ/q 


= 2,200 Joules/gram 




IN OTHER WORPS, IT TAKES ABOUT FIVE TIMES AS MUCH MEAT 
TO BOIL WATER ZOMPLETELy AWAy AS IT POES TO HEAT IT ALL 
THE WAy FROM 0° TO 100° \\ 


127 







IN THIS CHAPTER, WE 
REVIEWEP THE THREE 
STATES OF MATTER, 
WHAT HOLPS THEM 
TOGETHER ANP PULLS 
THEM APART. WE ALSO 
LEARNEP THE GAS 
LAWS, WHICH EXPLAIN 
EVERYTHING FROM 
CALCULATING ATOMIC 
WEIGHTS TO RUNNING 
REFRIGERATORS. 


REFRIGERATORS? 


Y£S.~ ELECTRICITy PRIVES A PUMP. 
THE PUMP COMPRESSES A GAS... THE 
GAS CONPENSES... 
HEATS UP, By 
THE GAS LAWS... 
PASSES THROUGH 
COILS... IS 
COO LEP BY 
n'» OUTSIPE AIR... 
EXPAN PS 
RAPIPLy ANP 
VAPORIZES... EN- 
POTHERMICALLy 
(Ptm PRAWS MEAT 
FROM INSIPE 
THE- SAy... IS 
THAT LEFTOVER 
SALAMI STILL 
SOOP? 


THERE EXISTS, By THE WAy, A FOURTH STATE OF MATTER. AT VERy HIGH TEM¬ 
PERATURE, ELECTRONS JUMP OFF THEIR NUCLEI-, ALL BONPS BREAK; ANP ALL 
SUBSTANCES TURN INTO A HOT PARTICLE SOUP CALLEP PLASMA- LUCKILY, 
THIS IS NOT SOMETHING CHEMISTS HAVE TO THINK ABOUT VERY OFTEN... 



Chapter 7 

Solutions 


WE’VE JUST LOOKEP AT 
STATES OF MATTER ONE 
AT A TIME... NOW LETS 
COMBINE TWO OF THEM- 
OR RATHER, LET’S COM¬ 
BINE SOMETHIN^, ANy- 
THIN&, WITH A LIQUIP. 
For INSTANCE: APP A 
PINCH OF TABLE SALT 
TO A FLASK OF WATER. 


( ALAKAZAM! ALAKAZORIPE/} 
V PI5APPEAR SOPlUM/ ✓ 
C DISAPPEAR CHLORIPE' J 



THE SALT, OF COURSE, COMPLETELy VANISHES. 



THE SALT, AS WE SAy, Pl$$OLVES IN THE WATER. 


129 










r SAy, WHERE’P 

you come 

FROM, ANyWAy? 


THE MASIC OF 
CARTOONING 




WHEN A SUBSTANCE PISSOLVES IN A LIQUIP, 
THE COMBINATION 15 CALLEP A SOLUTION. 
THE LIQUIP 15 THE SOLVENT, ANP THE 
PISSOLVEP MATERIAL 15 THE SOLUTE* 

Solute + Solvent 
—* Solution 


A PI550LVEP 50LIP FALLS APART INTO 
IT5 INPIVIPUAL CONSTITUENT PARTICLES, 
EITHER IONS OR MOLECULES. 6ASES ALSO 
PISSOLVE MOLECULE By MOLECULE. THIS 
EXPLAINS WHy SOLUTIONS ARE USUALLy 
TRANSPARENT. 



® 


(*))% 

X-- /Jll 




FOR EXAMPLE, SOPlUM CHLORIPE, NaCt, 
PISSOCIATES IN WATER INTO SINGLE 
Na* ANP CY IONS, WHICH BINP WITH 
THE WATER MOLECULES- 


CO > 


SU&AR-SUCROSE, C^H^O,,-BREAKS INTO 
WHOLE MOLECULES. (WATER MOLECULES 
LIKE ITS OH SROUPS.; 


'Q 


V 


k'i V°'T v~" 

Vs 0 

»' ? fc 'V 

1. d » * r 1 


' / s O 

o u ^ 


p. 


p. 


VINE5AR, A SOLUTION OF ACETIC ACIP, 
CH,C0 2 H, CONTAINS HyPROSEN IONS, H + , 
ACETATE IONS, CH ? CO^ ( ANP MUCH 
CH,C0 2 H STILL IN COMBINATION. 




k o > :• • 


- h 

'/ T 

O u 


‘ACTUALLY, A fOU/TION aw BE touv OR GASEOUS TOO. ANY HOM06EWEOU* mixture of two 
OR MORE $UB$TAN£E$ £ON$l7EREl? A SOLUTION, WHATEVER IT* PHAfE. 








LET'S LOOK MORE CLOSELY AT THE PISSOLVING PROCESS. IMAGINE A CHUNK OF 
MATERIAL IMMERSE? IN LIQUlP. IN OR PER TO DISSOLVE, SOME Of ITS PARTICLES 
MUST BREAK THE BONPS THAT HOLP THEM TOGETHER ANP FORM NEW BONPS WITH 
MOLECULES OF LIQUIP. SIMILARLY IMFS WITHIN THE LIQUlP MUST ALSO BE OVERCOME. 



EACH FREE SOLUTE PARTICLE ATTRACTS ONE OR MORE 
MOLECULES OF SOLVENT, WHICH CLUSTER AROUNP IT 
IN A SOLVENT "CAGE.” THIS PROCESS OF BREAKING 
ANP FORMING BONPS IS CALLEP SOLVATION. 



ALL THIS BONP REARRANGING 
MEANS THAT DISSOLVING IS 
A CHEMICAL REACTION. 

AMONG OTHER THINGS, THEN, 

IT HAS AN ASSOCIATE? ENTHAL¬ 
PY CHANGE, WHICH MAY BE 
POSITIVE OR NEGATIVE. 



FOR EXAMPLE, WHEN MAGNESIUM 
CHLORIPE, MqCl 2 , PISSOLVES IN 
WATER, IT HAS AN ENTHALPY 
OF SOLVATION 

AW = 119 kJ/mot 

HIGHLY ENPOTHERMIC/ A MERE 
4q Of MqCl 2 (* .04 2 mol) IN 
50mL C » 50g) Of WATER 
PROPS THE WATER’S TEMPERA¬ 
TURE BY 23.9 X (BY THE BASIC 
CALORIMETRY EQUATION). 


CHEMICAL COLP PACKS ARE IN FACT MAPE FROM 
MqCi 2 ANP OTHER SALTS THAT ABSORB HEAT 
WHEN PISSOLVEP IN WATER. 



131 






SOME LiQVlQ MIXTURES ARE NOT SOLUTIONS; 


WHEN I STIR POWPEREP MILK INTO 
WATER, THE SOLIP PARTICLES REMAIN 
IN VERY LAR6E SLUMPS OF MOLECULES. 
A MIXTURE LIKE MILK IS CALLEP A 
SUSPENSION, ANP SUSPENSIONS 
ARE OPAOUE. 



ANOTHER EXAMPLE WOULP BE PAINT, 
IN WHICH FLECKS OF PI6MENT ARE 
SUSPENPEP IN OIL OR SOME 6EL- 
LIKE MEPIUM. 

V___ 



AN EMULSION IS A SUSPENSION OF ONE LIQUIP IN ANOTHER. MAYONNAISE, 
FOR EXAMPLE, MAINLY CONSISTS OF TINY PROPLETS OF OIL SUSPENPEP IN 
VINE&AR. ORPINARILY, OIL ANP VINEGAR WOULP SEPARATE, BUT THE APPITION OF 
A SMALL AMOUNT OF MUSTARP ANP E66 YOLK STABILIZES THE EMULSION. 

LON& MOLECULES FROM THE YOLK BURROW 
INTO OIL PROPLETS. A POLAR “TAIL" 

STICKS OUT ANP ATTRACTS THE POLAR 
WATER MOLECULES IN VINEGAR, WHICH 
BLOCK THE PROPLETS FROM MER&IN&. 



* 







Concentration 

IS A MEASURE OF HOW MUCH SOLUTE IS 
PRESENT IN A SOLUTION RELATIVE TO THE 
WHOLE. 


FOR EXAMPLE, WEI&H OUT 35 q OF Na£l. THE CONCENTRATION OF THIS SOLUTION 
PUT IT IN A 6RAPUATEP CONTAINER ANP 15 35 q/L ANP MEASURES MASS OF 
APP WATER UNTIL THERE IS ONE LITER SOLUTE PER VOLUME OF 
OF SOLUTION. SOLUTION. 



OTHER POSSIBLE MEASURES (ALL USEP.'* 

MASS OF SOLUTE PER MASS OF SOLUTION 

VOLUME OF SOLUTE PER VOLUME OF SOLUTION 

MASS OF SOLUTE PER VOLUME OF SOLVENT 
(NOT THE SAME THIN& AS VOLUME OF SOLUTION'; 

MASS OF SOLUTE PER MASS OF SOLVENT 

PARTS PER MILLION (PPM) 

(A MASS-PER-MASS RATIO OF VERY PI LUTE SOLUTIONS; 

PARTS PER BILLION (PPB, EVEN MORE PILUTEP 


IT’S 600P 
TO HAVE 
OPTIONS' 


m 


WHEN THE SOLVENT IS WATER, WE CAN 
EASILy CONVERT FROM A MASS-VOLUME 
RATIO TO A MASS-MASS RATIO, BECAUSE 

ONE LITER OF WATER WE16H* 
ONE KILOGRAM. A liter of VERy 

PILUTE AQUEOUS SOLUTION, OF COURSE, 
WEIGHS THE SAME. 



m 







OUR FAVORITE MEASURE OF 
CONCENTRATION ACTUALLY 
TELLS YOU MOW MANY MOL¬ 
ECULES ARE DISSOLVED RELA¬ 
TIVE to volume. MOLARITY, 

OR MOLAR CONCENTRATION, 
IS THE NUMBER OF MOLES OF 
SOLUTE PER LITER OF SOLU¬ 
TION. WE WRITE 

M * MOLES/LITER. 


RATS / 


J NO, 
MOLES' 


c ? 



( AM! IT’S A \ 
' MEASURE OF 
600DNE55 THEN! 


^ SORRY, ITS 

MOLARITY, not 
-r MORALITY... i 




WHAT’S THE MOLARITY OF OUR g/L 
SALT SOLUTION? ONE MOLE OF NaO 
WEIGHS 50 A q, SO WE HAVE 


55 g 

50.4 q/mol 


= 0.6 mol NaCl 


IN A LITER OF SOLUTION. THE MOLARITY 
IS 0.6 M. 


WE USE SQUARE BRACKETS, [ ], TO 
DENOTE MOLAR CONCENTRATION OF 
ANY “SPECIES" (I.E., ANY PARTICULAR 
MOLECULE OR IOW IN SOLUTION. 
HERE, SINCE NaCl DISSOCIATES 
COMPLETELY IN SOLUTION, 

[Nc* + ] = om 
icr\ = 0.6M 

IN A 1 M SOLUTION OF Kla^SO^, 
WHICH ALSO FULLY DISSOCIATES, 

[Na + ] S 2M 
[SO/'] * 1 M 

THERE ARE TWO MOLES OF Na + FOR 
EACH MOLE OF Na 2 50 4 . 



m 





THE EQUIVALENT 
WORP FOR LIQUlP- 
LIQUIP INTERACTION 
IS 

TWO LIQUIPS ARE 
MISCIBLE IF THEY 
PISSOLVE IN ONE 
ANOTHER ANP 
IMMISCIBLE IF, LIKE 
OIL ANP WATER, 
THEY SEPARATE. 



A 


■ ' WATER 


. FOOP 
COLORING 


IMMISCIBLE 


MISCIBLE 


IBS 




LIKE TENP$ TO DISSOLVE UKE. A pour solvent (such as water; 
TEN PS TO PiSSOLVE (OR MIX WITH; OTHER POUR COMPOUNPS. HERE PIPOLE- 
PIPOLE OR PI POLE-ION ATTRACTIONS PRIVE SOLVATION. FOR INSTANCE: 


METHANOL, CH,OH, IS POLAR ANP FORMS ITS COUSIN METHANE, CH„, IS UTTERLY 
A HYPROSEN BONP WITH WATER, WITH SYMMETRICAL ANP NONPOUR. WATER 

WHICH IT WILL MIX IN ANY AMOUNT. SHUNS IT, ANP ITS SOLUBILITY IS VERY 



MOLECULAR $IZE: 

BI6, HEAVY MOLECULES 
TENP TO BE LESS 
SOLUBLE THAN SMALL, 
LI6HT ONES. SOLVENT 
MOLECULES FINP IT 
HARP TO “CA6E” BI6 
PARTICLES. 


'O' 

v • 


A 


^ I MEAN, 
WHERE PO 
YOU START? 








VH> 








TEMPERATURE 

ALSO AFFECTS 
SOLUBILITY. AS 
TEMPERATURE RISES, 
A&ITATEP MOLECULES 
OR IONS BREAK TMEIR 
BONPS MORE EASILY, 
SO SOLUBILITY 
USUALLY SOES UP. 
EXCEPTIONS EXIST, 
HOWEVER, AMP THE 
EFFECT IS SOME¬ 
TIMES SLIGHT. 



TEMPERATURE CO 


FOR PISSOLVEP 
6ASES, PRESSURE 
AFFECTS SOLUBIL¬ 
ITY. TO BE PRECISE, 

the PARTIAL 
PRESSURE OF A 

SAS ABOVE THE 
SOLUTION! AFFECTS 
THE AMOUNT OF 
6AS THAT WILL PlS- 
SOLVE. THE HISHER 
THE PARTIAL 
PRESSURE, THE 
GREATER THE 
SAS’S SOLUBILITY. 




LOWER PRESSURE 
LOWER CONCENTRATION 


HISHER PRESSURE 
WISHER CONCENTRATION 



SOFT PRINKS, WHICH CONTAIN 
P1SSOLVEP C0 2> ARE BOTTLEP 
AT HISH PRESSURE TO INCREASE 
THE AMOUNT OF PISSOLVEP SAS. 
WHEN THE CAP IS REMOVEP, 
PRESSURE EASES, ANP CO z 
FIZZES OUT OF SOLUTION. 


137 





Freezing 


GENERALLY SPEAKING 
PISSOLVEP MATERIAL 
LOWERS THE FREEZIN6- 
POIMT. SOLUTE PARTIBLE* 
PISRUPT the normal 
COHESIVE FORCES 
WITHIN THE SOLVENT, 
MAKING IT HARPER FOR 
THE SOLUTION TO 
SOLIPIFY. THE HIGHER 
THE CONCENTRATION, 
THE LOWER THE 
FREEZING POINT. 


k 


J EEK/ \ 
' I’M BEIN6- 
PULLEP POWN 
BY MOLES' 


IT’S 50 HARP 
TO CRYSTALLIZE 
► SOMETIMES... T 


fe 


Vo... 



FOR EXAMPLE, IN AN ICE 
CREAM MAKER, A BUCKET OF 
CREAM, PISSOLVEP SU6AR, 
ANP FLAVOR IS SURROUNPEP 
BY ICE, WHICH MAY BE AT 

-v to -5‘c. 


WHEN SALT IS APPEP, THE 
ICE MELTS. THE BELOW- 
ZERO SALT WATER NOW 


NOW THE CREAM CAN BE 
RAPIPLY COOLEP BELOW 
0°C, LIQUIP WATER ALSO 


MAKES CONTACT WITH THE HAS A HIGHER HEAT 


FULL SURFACE OF THE 
BUCKET. 


CAPACITY THAN ICE, ANP SO 
COOLS MORE EFFICIENTLY. 



ICE TOUCHES THE CREAM CONTAINER 
IN ONLY A FEW PLACES. 


EFFICIENT HEAT TRANSFER 


ICE CREAM RARELY FREEZES TOTALLY. AS 
THE LIOUIP FREEZES, SU6AR BECOMES 
MORE CONCENTRATE? IN THE REMAINING 
SYRUP, SO ITS FREEZING POINT PROPS 
EVEN LOWER, ANP SOME OF IT REMAINS 
UNFROZEN. THAT’S WHY ICE CREAM IS 
USUALLY SOFT. _ 







m 



Boiling 


PISSOLVEP 
MATERIAL UPS 
THE BOILING 
POINT, ANP 
THUS EXTENPS 
THE RANGE OF 
THE UOUIP 
STATE IN BOTH 
PIRECTIONS- 



LOWEREP 
FREEZING PT 


THIS IS AGAIN A RESULT OF SOLUTE- 
SOLVENT INTERACTIONS. SOLVENT 
MOLECULES THAT ARE ATTACHEP TO 
SOLUTE PARTICLES FINP IT HARPER 
TO ESCAPE INTO THE GAS PHASE. 

' 

>-S *CcOME ON! 

^ 

BUSY.' I 


EVAPORATION IS REPUCEP, ANP THERE¬ 
FORE SO IS VAPOR PRESSURE, P v . 




PRESSURE OF 
VAPOR JUST 
ABOVE UQUJP 
SURFACE* 


SO A HIGHER TEMPERATURE IS NEEPEP TO 
BRINS THE VAPOR PRESSURE UP TO THE 
PREVAILING EXTERNAL PRESSURE. (RECALL 
THAT BOILING OCCURS WHEN P v = EXTERNAL 
PRESSURE.) 


MAYBE THIS IS WHY CHEFS 
APP SALT TO WATER FOR 
COOKING- SPAGHETTI. THE 
SALT SOLUTION BOILS AT A 
TEMPERATURE ABOVE \OO a C 
CAT ONE ATM, ANYWAY), 

ANP THE SPAGHETTI IS 
PONE SOONER. ALSO, IT 
TASTES BETTER... 


/i c 


% 


' I HAVE NO 
PATIENCE WITH 
STIFF SPAGHETTI! 


‘SEE CHAPTER 6 , PAGE 110. 


139 







So What! 






Chapter 8 

Reaction Rate and 
Equilibrium 


-- 

IN CHEMISTRY WE CARE ABOUT NOT ONLy WHAT REACTS, BUT ALSO HOW 
FAST. BLACK POWPER EXPLOPES IN A FLASH, WHILE THE SD6AR IN yoUR 
COFFEE NEVER SEEMS TO PISSOLVE FAST ENOUGH. WE TRy TO SPEEP UP 
ENVIRONMENTAL CLEANUP ANP RETARP RUST ANP A6IN6-. IN OTHER WORPS, 

RATES MATTER/ 



“AT FIRST SI&HT, NOTHING SEEMS MORE OBVIOUS THAN THAT EVERYTHING HAS A 

BEGINNING ANP AN ENP." 

—SVANTE ARRHENIUS, 1903 NOBEL PRIZE WINNER IN CHEMISTRY 


Ml 



WHAT’S THE RATE OF A (CHEMICAL REACTION? WE BE&IN WITH THE ULTRA-SIMPLE 

as e of ONuy one reactant: 


A — PROPUCTS 

HERE THE REACTION RATS 

r A IS THE RATE AT WHICH 
REACTANT A IS USEP UP OVER 
TIME. IT MAy BE EXPRESSEP IN 
MOLES PERSECONP. 

IF A IS IN SOLUTION, r A 
USUALLy REFERS TO THE RATE 
AT WHICH CONCENTRATION [A] 
CHANGES, IN MOLES PER LITER 
PER SECONP, ANP IF A IS A 
6AS, r A MAy REFER EITHER TO 
CONCENTRATION OR PARTIAL 
PRESSURE P A > WHICH AMOUNT 
TO THE SAME THIN&. 



FOR EXAMPLE, IN THE LOWER ATMOSPHERE, SUNLIGHT FALLING ON NITROGEN 
PIOXIPE, N0 2 , CAUSES IT TO BREAK INTO NITRIC OXIPE, NO, ANP A LOOSE 
OXy&EN ATOM (CALLEP A FREE RAPICAL> 

N0 2 -*• NO + 0 

(THE FREE OXySEN 60ES ON TO BINP WITH 0 2 TO FORM OZONE, 0,. OZONE 
ANP THE NITR06EN OXIPES ARE AMON& OUR NASTIER AIR POLLUTANTS.} 









AT MIPPAY, N0 2 MAKES UP ABOUT 20 PART* PER BILLION OF THE AIR-20 MOL 
OF N0 2 PER BILLION MOL OF AJR-OR 2 O MOL OF N0 2 IN 24.4 X 10 9 L OF AIR 
(AT 25’C). *0 MOLAR CONCENTRATION I* [N0 2 ] * 20/(24.4 X 10 9 ) = 0.2 X 10" 10 
MOL/L. LET’* TAKE AN AIR SAMPLE, ANP MEASURE [N0 2 ] EVERY 40 SECONPS AS 
IT PECOMPOSES. WE WRITE [A] t FOR THE CONCENTRATION OF N0 2 AT TIME t. 



t 

(SEC.) 

[A] t 

(x io w mol/u 

0 

0.20 

40 

5.00 

00 

4.10 

120 

2.90 

160 

2.09 

200 

1.45 

240 

1.02 

200 

.72 

320 

.51 

360 

.36 


[A]* 
C[A] 0 V2 
([A y/4 
C£A3^/0 

W/u 


THE REACTION CERTAINLY SLOWS OVER TIME. IN 1 0 w LITERS OF AIR, 2.4 MOL 
^Alo'CA]^) WERE USEP UP IN THE FIRST AO SEC., BUT ONLY 0.21 MOL IN 
THE 40 SECONPS BETWEEN t - 200 ANP t - 320 ([A] w - [A] ?2 *>. 


THE PECLINE HAS A PATTERN: 

HALF THE REMAINING 
REACTANT IS CONSUMEP 
EVERY 90 SECONPS. at 

t - 00 SEC., HALF THE N0 2 IS 
LEFT... AT 160 SEC., A FOURTH 
REMAINS... AT 240, AN EIGHTH, 
ETC. WE SAY THE REACTION HAS 

A HALF-UFE, h, of 00 

SECONPS. PURIN6 ANY INTER¬ 
VAL OF LEN6TH h, HALF THE 
REACTANT IS CONSUMER. IN a 
HALF LIVES, THEN: 



143 




A SIMPLE MOPEL ACCOUNTS FOR THIS BEHAVIOR. START WITH A B16 BUNCH OF 
MOLECULES OF REACTANT A. ANP IMA6INE THAT EVERy MOLECULE HAS THE 
SAME PROBABILITY OF PECOMPOSINS. THEM A FiXEP FRACTION OF THE WHOLE 
WILL REACT IN EACH UNIT OF TIME. 



OO' 


Oo 


O 0 # O 

•°o°g 

o°o*S 


° oo° 
o o o 


IN OTHER WORPS, THE REACTION RATE (NUMBER OF MOLES OR MOL/L 
PECOMPOSINS PER UNIT TIME) IS PROPORTIONAL TO THE QUANTITY OF 

REACTANT present (number of moles or mol/l;. so we can write a 

SECONP FORMULA FOR THE REACTION RATE; AT ANY SIVEN TIME, 


r 




kfAl 


k IS A CONSTANT CALLEP THE RATE CONSTANT BY CONVENTION, k IS 
ALWAYS A POSITIVE NUMBER, SO THE MINUS SISN IS NECESSARY TO MAKE 
r NEGATIVE, MEANING [A] IS PECREASIN6. 


OH, IT 
SHRINKS! I 
SET m 











MOTE - - MATH-AVERSE REAPERS MAY SKIP THIS PASE. OTHERWISE, KEEP REAPING 


WE CAN EVALUATE k FROM THE PATA. 
START WITH THE FIRST EQUATION 

[A] nh = i-m, 

[A] DECREASES EXPONENTIALLY 

CAS THE EXPONENT OF 2 IN THIS EQUA¬ 
TION;. IN PARTICULAR, [A] NEVER 
REACHES ZERO, theoretically, 

THE REACTION NEVER ENPSI 



h IS AN AWKWARP TIME UNIT-IT VARIES FROM ONE REACTION TO ANOTHER. WE WANT 
A FlXEP UNIT OF TIME, t (PAYS, SECONPS, WHATEVER’S APPROPRIATE;. THEN 


t - nh, or n = t/h 
ANP WE CAN WRITE 
[A] t = 2“ t/h [A 1 0 

TAKING THE NATURAL LOS OF BOTH SIPES, 

In [A] t = + In [A]* 

SETTING k = C1/W In 2, WE FINP-. 

In [A] t = -kt + in[A] 6? 



THAT IS, THE PLOT OF ln[A] t ASAINST t IS A STRAIGHT LINE WITH SLOPE -k. 
ONE CAN SHOW CUSINS CALCULUS; THAT THIS IS THE SAME k AS IN r A = -k[A]. IN 
OUR N0 2 EXAMPLE, THEN, 

k = a/0O SECXln 2) * C1/0P S UXo.693) - 0.0097 SEC -1 . THAT IS, 

0.97% OF THE N0 2 6AS IS CO NSUMED EVERY SECOND. 



A REACTION WITH r = -k[A] IS CALLEP A 
FIRST-ORDER REACTION: IT SOES AS 
THE FIRST POWER OF A SIN6LE CONCENTRA¬ 
TION. YOU CAN CHECK EXPERIMENTALLY IF 
A REACTION IS FlRST-ORPER BY SRAPHIN& 
In [A] t ASAINST t ANP SEEINS IF IT’S A 
STRAIGHT LINE. IF SO, THE RATE CONSTANT 
IS THE NEGATIVE OF THE SLOPE. 








Collision Course 


MOW ABOUT A SECONP-ORPER 
REACTION? THAT MI6HT LOOK LIKE 


A + B 


PROPUCTS 


MERE r A = r B BECAUSE THE REACTION 
REMOVE'S MOLECULES OF A ANP B 
WETHER IN PAIRS. THE REACTION 
RATE r IS THEN TAKEN TO BE 

r = r* = r n 



o 








HOW OFTEN PO 
PARTICLES COLLIPE? IT 
PEPENPS ON THEIR 
CONCENTRATION COR 
PARTIAL PRESSURES 



m 






IMAGINE THAT A VOLUME OF 6AS OR ELU¬ 
TION 16 PIVIPEP INTO COUNTLESS TINy COM¬ 
PARTMENTS. IF TWO PARTICLES SHARE A 
COMPARTMENT, WE’LL CALL THAT A 
COLLISION. 


IF [B] IS CONSTANT THEN CHAN6IN6 
[A] CHANGES THE NUMBER OF A-B 
COLLISIONS PROPORTIONALLY. (HERE A 
ARE BLACK ANP B ARE WHITE.; 




THE SAME IS TRUE WHEN [B] IS CHAN6EP, SO THE FREQUENCY OF 
COLLISIONS MUST BE PROPORTIONAL TO [A][B], OR P A P B , IF A 
ANP B ARE SASES. 


NOT ALL COLLISIONS RESULT IN REACTION. THE ONES THAT PO ARE CALLEP 

EFFECTIVE, we assume that the ratio of effective collisions to 

TOTAL COLLISIONS IS CONSTANT (AT A FlXEP TEMPERATURES 



AMAZIN6 THAT THE 
LITTLE THINSS EVER 
MEET AT ALL/ 


SO: REACTION RATE 
EQUALS RATE OF 
EFFECTIVE COLLISIONS, 
WHICH IS PROPOR¬ 
TIONAL TO RATE OF 
TOTAL COLLISIONS, 
WHICH IS PROPOR¬ 
TIONAL TO [A][B] 

OR P A P B . CONCLUSION: 


r = -k[A][B] 

k A POSITIVE CONSTANT 


WE SAY THE REACTION IS FIRST ORPER IN A, FIRST ORPER IN 0, ANP SECONP 
ORPER OVERALL. 





M7 










Example 


WE’VE ALREAPy SEEN THAT IN PA/U6HT 

kio 2 — MO + 0 

ANP THE MONATOMIC OXyCEN COES 
ON TO MAKE OZONE 

0 + 0 2 —♦ 0 3 

SO OVERALL 

U0 2 + 0 2 — MO + 


AT NICHT, THE REVERSE REACTION 
TAKES PLACE: 



THIS REACTION HAS RATE r = RATE OF CONSUMPTION OF NO = RATE OF CONSUMPTION 
OF 0 3 ANP IS CIVEN gy 

r * -k[M0][0,] k = 1.11 X 1C7 7 M' 1 SEC' 1 

A TypICAL NO CONCENTRATION IS AROUNP 24 PPB*. WHICH AS BEFORE 6-IVES MOLAR 
CONCENTRATION [NO] AS (24 MOL NO/24.4 X IP 9 L OF AIR) * 10 9 M. [0 ? ] IS 
AROUNP TWICE THAT, OR 2 X 10' 9 M. 


A BIT OF CALCULUS 
PROPUCES THIS PLOT 
OF THE CONCENTRA¬ 
TIONS. THE REACTION 
COES OUlCKLy: IT'S 
ESSENTIALLy OVER IN 
FIVE OR SIX MINUTES. 



£ 

LU 

t: 


z 

o 


to 


or 


£ 


a 


o 



TIME CM INJ 

NOTE: THIS CRAPH IS COOP ONLy FOR AN ISOLATEP 
SAMPLE. TO PREPICT CONCENTRATIONS IN THE ENVIRON¬ 
MENT, WE NEEP TO KNOW THE RATES OF ALL REACTIONS 
THAT CONSUME ANP PROPUCE NO ANP 0 3 , AS WELL AS 
HOW MUCH ENTERS THE AIR FROM ODTSIPE SOURCES. 


* PARTS PER BILLION 


143 





Reactions Up Close 

WHY ARC SOME COLLISIONS EFFECTIVE, ANP SOME ARE NOT? 


ONE REASON IS PARTICLES* 
RELATIVE ORIENTATION. 
TWO MOLECULES MAY 
NEEP TO PRESENT A 
CERTAIN “FACE” TO EACH 
OTHER BEFORE THEY CAN 
COMBINE. FOR EXAMPLE, 
WHEN A HIGHLY POLAR 
MOLECULE OF HO MEETS 
ETHENE, CH 2 CH 2 , A LOT OF 
ANGLES PON’T WORK. 



o 


> 


V. 



" - "I « NOPE' } 

0 

# ®* ^T) 


BUT WHEN THE POSITIVE POLE OF HO MEETS CH 2 £H 2 ’S VERY NEGATIVE POUBLE 
BONP, ELECTRONS SHIFT—FIRST, ONE 60ES TO HYPR06EN {IT’S CLOSER). 




THE INTERMEPIATE 
STATE, BEFORE THE 
CHLORINE IS BON PEP, IS 
CALLEP A TRANSITION 
STATE- HERE THE 
TRANSITION STATE 
APPEARS ONLY WHEN 
THE REACTANT 
MOLECULES ARE 
ORIENTEP PROPERLY. 



149 





ANOTHER FACTOR AFFECTING 
WHETHER COLLISIONS LEAP TO 
REACTIONS IS HOW FAST THE 
PARTICLES ARE MOVING. 



WHEN FLYING H 2 ANP 0 2 GAS 
MOLECULES COLLIPE, FOR INSTANCE, 
THEIR NE&ATIVELy CHARGEP ELEC¬ 
TRON CLOUPS REPEL EACH OTHER 
ANP ACTUALLy BECOME PISTORTEP. 



BUT IF INITIAL ICE. IS HIGH ENOUGH 
TO OVERCOME ELECTRIC REPULSION, 
THINGS CAN BREAK APART. 



H 2 + 0 2 — 2H + 20 


IF THE KINETIC ENER&y OF THE 
COLLISION IS TOO LOW, THE MOL¬ 
ECULES SIMPLy BOUNCE AWAy. 



IF A FREE 0 MEETS AN H t , ELECTRIC 
REPULSION AGAIN PEFORMS THE ELEC¬ 
TRON CLOUPS. 



IF THE COLLISION ENERGy IS SUFFI¬ 
CIENT, ELECTRONS ARE REARRANGE?, A 
WATER MOLECULE FORMS, ANP ENERGY 
ESCAPES (THE REACTION IS EXOTHERMIC;. 



H 2 + 0 —► W 2 0 A H<0 


v?o 





50-THE 6A5 MIXTURE NEEP5 50ME EXTRA ENERGY TO 6ET THE REACTION 
5TARTEP: A 5PARK OR A FLAME, 5AX TO ENERGIZE 50ME PARTiaE5. 



BUT OW£E IT 5TART5, H 2 + 0 — H 2 0 15 50 gXOTMCRMIC THAT IT EXZITE5 
THE PARTIZLE5 AROUNP IT, AMP THE WHOLE REACTION RU5HE5 FORWARP WITH 
A 5UPPEM, LOUP- 



THI5 15 ONE REA50N WHY ZHEMI5T5 ARE ALWAV5 HEATIN& THIM&5... WE HAVE 
TO 5UPPLy THAT IWITIAL ENER6Y KICK TO 6ET REA0TI0N5 ‘OVER THE HUMP." 



50RRy. you HAVE 
TO WAIT UNTIL 
CHAPTER 10 FOR 
THE AKI5WER TO 
THAT ONE/ 






NEARLY EVERY COMBINATION REACTION WORK3 THE 3AM£ WA^ IT NEGP3 AN 
APPEP ENERGY PU3H TO BRIN& THE REACTANT3 TOGETHER. THI3 B003T 13 
CALLEP THE ACTIVATION ENER&y OF THE REACTION, G a . IN OTHER WORP3, 
CHEMICAL REACTION3 ARE NOT JD3T LIKE FALLING POWNHILLI 



THE OBVIOU3 WAy TO 6ET A REACTION MOVING FA3TER, THEN, 13 TO MAKE 
MORE OF THE PARTICLE3 EXCEEP THE ACTIVATION ENERCY—IN OTHER WORP3, 
By RAI51N6 TEMPERATURE, then a higher fraction of COLLI3ION3 
WILL BE EFFECTIVE. 


LOW£R T CV RV£ 


tSs'-s is 




THIS 6RAPH SHOWS THE ENER&V PISTRI- 
BUTIOM OF A 6ROOP OF PARTICLES AT 
TWO DIFFERENT TEMPERATURES. AT HI6HER 
TEMPERATURE, A GREATER PROPORTION OF 
PARTICLES MEASURE!? W THE AREA UNPER 
the curve; HAVE KE > E a . 


HJ6HER T CURVE 


ENER^y 


152 





Catalysts, or Raising 


YOU’RE PROBABLY NOT 
SURPRISE? TO HEAR THAT 
RAISING TEMPERATURE 
ACCELERATES REACTIONS* 
AFTER ALL, WE’VE ALL 
SEEN IMAGES OF CHEM¬ 
ISTS COOKING THINGS UP. 
MAYBE WE’VE EVEN 
TURNEP UP THE FLAME A 
FEW TIMES OURSELVES. 




NOW, HOWEVER, WE CAN BE MORE PRECISE. SINCE r = -k[A][B] FOR OUR 
SECONP-ORPER REACTION, WE CAN SAY THAT BOOSTING TEMPERATURE RAISES k, 
THE REACTION CONSTANT. 


ARE THERE OTHER WAYS 
TO RAISE k? BASE? ON 
THE PRECEPIN6- PIS- 
CUSSION, WE MI6HT 
WONPER IF IT’S POS¬ 
SIBLE TO REPUCE A 
REACTANT’S UNFAVOR¬ 
ABLE ORIENTATIONS, 

OR LOWER THE ACTI¬ 
VATION ENERGY. THIS 
IS WHERE £ATALY$T$ 
COME IN. 



«wrmiM LMtrr* when t too h/£H> everything- sha kg* apart, amp the reaction & wsruptep. 


A CATALYST IS A SUBSTANCE THAT 5PEGPS UP A REACTION BUT ITSELF EMER6ES 
FROM THE REACTION UNCHAN6EP. 


FOR EXAMPLE, THE CATALYTIC. 
CONVERTOR IN A CAR ENGINE 
5PEEP5 THE PETOXlFlCATlON OF 
EXHAUST 6A5ES. ONE SUCH REAC¬ 
TION BREAKS CAUSTIC NITRIC 
OXIPE TO N2 ANP 0 2 : 

2 NO — N 2 + 0 2 

IN THE CONVERTOR CHAMBER, 
PLATINUM, RHOPIUM, ANP PALLA- 
PIUM SCREENS BINP TO THE 6AS 
MOLECULES VIA VARIOUS IMF*. 





THE CATALYST BOTH ALI6NS THE MO MOLECULES FAVORABLY ANP CUTS 
ACTIVATION ENERGY BY PULLIN6 A6AINST THE N-0 BONP-PROBABLY- 
THE EXACT MECHANISM 15 UNKNOWN. 


— --- - ■, 

CATALYSTS ALSO PROBABLY ENABLEP THE ORIGIN Of LIFE. THE CHEMICALS 
OF LIFE COR PRE-LIFE) WERE TOO BI6 ANP UNGAINLY TO MAKE PROGRESS BY 
RANPOM COMBINATION... BUT IF CAS SEVERAL THEORIES SUREST} THEY WERE 
ANCHOREP AT ONE £NP TO A CHAR6EP SURFACE, SUCH AS CLAY ON THE OCEAN 
FLOOR, THEY WOULP BE MUCH MORE LIKELY TO EN6A6E IN “600 P” REACTIONS' 



1S4 



Higher-order Reactions, Maybe 


WE SAW THAT 

A + B —* PROPUCTS 

IS A SECONP-ORPER REACTION 
WITH RATE r = -k[A][B]. THIS, 
BY THE WAY, INCLUPES THE SPECIAL 

case when A AMP B ARE 
THE SAME- THE REACTION 

A + A ^ propucts 
HAS A RATE - k[A] 2 . 


^ SOMETIMES V 
A ANP A HAVE TO 
SHARE A CQ.ll! 


O o 


Xy 

0 

: ! 

0 


) 

o 

1 

i 

00 

O 



NOW WE WOULP LOVE TO EXTENP THIS TO MORE COMPLEX REACTIONS. WE 
MI6HT HOPE* FOR EXAMPLE, THAT RATE LAWS WOULP BE ANALOGOUS: 


2A + B — PROPUCTS r = 
2A + 3B —> PROPUCTS r - 
ANP GENERALLY 

aA + bB —. PROPUCTS r = 


-k[A] 2 [B] (THIRP ORPER; 
'k[A] 2 [B ] 3 (FIFTH ORPER; 

'k[A] a [B] b (ORPER a + \>V 


J SO VERyl 
REASONABLE. 


WE WOULP LOVE TO 
SAY IT, REAPER, BUT 
UNFORTUNATELY WE 
(ANT, BECAUSE IT’S 

false. 

RATES OF REAL-LIFE 
REACTIONS CAN’T BE 
PREPICTEP FROM 
THEORY, BUT MUST 

BE MEASURED 
EXPERIMEMTAUtt 



’WE HAVE TO BE A LITTLE CAREFUL ABOUT WHAT WE IWEAM BY r. IT'S THE RATE AT WHICH aA + fc>B IS 
CONSUME?. THAT IS, r = (l/cOr A * (1/b)r e . 


m 





IN FACT, EVEN THE REACTION (A + B —► PROPUCTS) SOMETIMES POESN’T BEHAVE AS WE 
CLAIMS?. YES, REAPER, MUCH OF THE FIRST HALF OF THIS CHAPTER IS SIMPLY UNTRUE' 


t 


USEFUL? CERTAINLY' 
CONCEPTUALLY VALIP? 
- r SORT OF... i-' 


V- 

M 



WE COVERTLY MAPE A SIMPLIFYING 
ASSUMPTION, YOU SEE, BY IMAGI¬ 
NING THAT REACTIONS HAPPEN IN A 

SINGLE STEP, 

a <c ?-£p 

( so... why L*4vVt 

K NOT? O 


BUT IN REALITY THEY OFTEN TAKE SEVERAL 
STEPS TO COMPLETE... SORRY' 


° o 




FOR INSTANCE, WHEN WE WRITE 2A + B, ARE WE 
REALLY TO IMAGINE THREE PARTICLES COLLIPING 
AT ONCE? NOT LIKELY... MORE PROBABLY, A MEETS 
0 TO FORM AB, THEN ANOTHER A COMES ALONG.., 


O 


c r%. 


o 


IVE BEEN 
LIEP TO... 



ONE-STEP REACTIONS ARE 

callep ELEMENTARY... 

ANP IT IS TRUE THAT AN 
ELEMENTARY REACTION 
aA + bB —» PROPUCTS 
HAS A REACTION RATE OF 

r = -k[A]“[B] b . 


1SS 






IN A MULTI-STEP 
REACTION, INTER- 
MEDIATE STEPS ARE 
OFTEN UNCLEAR... 
THINGS &0 BY TOO 
FAST TO OBSERVE. 
BUT THIS MUCH IS 
TRUE: THE SLOWEST 
INTERMEDIATE 
REACTION RATE 
PETERMINES THE 
OVERALL RATE. 


TO SEE THIS, IMAGINE A WASHER-PRYER COMBO THAT 
PROCESSES A LOAP OF PIRTy CLOTHES IN EXACTLY 24 
HOUR*. LET’S LIFT THE UP ANP SEE HOW IT WORKS 



WASHING, rT SEEMS, IS PONE MANUALLy By ILL-TRAINEP, UNCOOPERATIVE WEASELS 
WHO TAKE 29.999 HOUR* TO PO A LOAP. THE PRyER IS A NUCLEAR BLAST 
FURNACE THAT CRISPS yOUR CLOTHES IN A MILLISECONP. 



PRO/EW 1 ■ RATE = ONE LOAP/PAY PROCESS 2 RATE » 06.4 MILLION LGAPS/PAY 

OVERALL PROCESS: RATE = ONE LOAP/PAY 


NOW IS IT CLEAR 
THAT THE OVERALL 
RATE IS THE RATE 
OF THE SLOWEST 
STEP? WHEN THE 
WEASELS ARE PONE, 
THE “REACTION” IS 
ALL BUT OVER! 



CHEMICAL EXAMPLE: IOPIPE ION 
REPUCES PEROXypISULFATE 

S 2 O 0 Z '+ 21"—* 2SO/- +1 2 

LOOKS THIRP-ORPER, BUT 
EXPERIMENT SAyS SECONP- 
ORPER, WITH 


r * -k:s 2 0 g 2 '][r] 



CHEMISTS PROPOSE TWO 
ELEMENTARy STEPS: 

s 2 o/-+ r—> 2so/-+ r 
r + r — i* 

THE FIRST REACTION’S 
THEORETICAL RATE 

r = -k[S 2 0/-][r] 

MATCHES THE OBSERVEP 
RATE OF THE OVERALL 
REACTION. THE SECONP 
REACTION PRESUMABLY 
HAPPENS VERY FAST. 


157 






Equilibrium 


• •• 


15 A 5TATE OF 

pyNAMI£ BALANCE. 

IN NATURE, WE OFTEN 
FINP TWO PROCE55E5 
THAT UNPO EMM 
OTHER-EVAPORATION 
ANP CONPEN5ATION, 
FOR 1N5TANCE. WHEN 
THE PROCE55E5 UNPO 
EACH OTHER AT THE 

SAME RATE, noth¬ 
ing APPEAR5 TO BE 
CHANGING. THAT’5 

EQUILIBRIUM- 


IF I 501U My CL0THE5 AT THE 5AME RATE THEY’RE 
WA5HEP ANP PRIEP, I ALWAY5 HAVE THE 5AME AMOUNT 
OF CLEAN CL0THE5. 


I’M IN EQUILIBRIUM 
WITH WEA5EL5... / 


FILTHY PIG. 



MANY CHEMICAL REACTI0N5 ARE 

REVERSIBLE. 

aA + bB cC + dP 

REACTANT5 A ANP B COMBINE 
TO MAKE C ANP p... BUT IF 
EVERYTHING REMAIN5 MlXEP 
TOGETHER, C ANP P CAN FlNP 

each other to make a anp b. 









® 



o 

® o 






WE 5AW AN EXAMPLE IN CHAPTER A- 

CaCO ,(«> *=* CaOW + COJ 

LIME5T0NE WA5 COOKEP TO FORM QUICKLIME 
ANP CARBON PIOXIPE GA5. LATER, THE WHfTE- 
WA5H MAPE FROM CaO REACTEP WITH CO t FROM 
THE ATM05PHERE TO MAKE CaCO-, AGAIN. 


CHALKY/ 






IF THE C0 2 HAP NOT BEEN ALLOWEP TO 
E5CAPE IN THE ORIGINAL REACTION (If, IF 
THE REACTION HAP OCCURREP IN A CL05EP 
VE55EU, 50ME OF THE GA5 WOUL? HAVE 
RECOMBINEP THEN ANP THERE 













MOW IMAGINE A REACTION 
VEGGEL CONTAINING THE 
REACTANTG A ANP 0. 


o ® o 

o® ® 

® ® ® 

© ® ® 


THE FORWARP REACTION BEGING AMP MAKEG 
C ANP P AT A RATE r F . AG C ANP P 8UILP UP, A 
FEW OF THEM FINP EACH OTHER, ANP THE REVERGE 
REACTION PEG-1 NG AT A LOW RATE r REV . 


© ® 





o 





AT FlRGT, r F >r RCV , ANP THE REACTION “GOEG TO 
THE RIGHT.” A ANP 0 ARE CONGUMEP FAGTER THAN 
THEY ARE REPLENIGHEP, ANP C ANP p BUILP UP 
FAGTER THAN THEY ARE CONGUMEP. 



© 








® 





©~® 



Q 0 jfa 


®kU© 






® 


IN OTHER WORPG, AG LONG AG 
r F >r REV- [A] ANP [B] FALL 
ANP [C] ANP [P] RIGE. 


® _ 

J© 


t gift! 




® © 



PUT RATEG ARE 
PROPORTIONAL TO 

Cpowerg of; 

CONCENTRATIONG. GO 
AG LONG AG r F >r Rgv , 
r F MUGT FALL ANP 
r Rcv MUGT RIGE. THE 

REACTION CON¬ 
TINUES UNTIL 


r F * r 


REV- 


AT THIG POINT EACH GUPGTANCE IG PEING CONGUMEP AT 
THE GAME RATE IT IG PEING REPLENIGHEP. THE CONCEN¬ 
TRATIONG [A], [P], IQ, ANP [P] MO LONGER CHANGE. 
THE REACTION HAG REACHEP EQUILIBRIUM- 


A LOT IG 
GOING ON, 
BUT VERY 
QUIETLY! j 

3P 


© 


h(W* 


1G9 







AMP A 
LITTLE 
WORE 
MATH- 



NOW WE MAKE AN UNWARRANTEP 
ASSUMPTION; SUPPOSE THE REAC¬ 
TION ORPERS ARE SIVEN BY THE 
STOICHIOMETRIC COEFFICIENTS 
a, b, c, ANP d. THAT IS; 

r F = -k F [A]“[B] b 

(HERE k F ANP k R£V ARE THE 
FORWARP ANP REVERSE RATE 
CONSTANTS.) 


AT EQUILIBRIUM, THEN, THE RATES 
ARE EQUAL; 

k F [A ns? = 

REARRANGING, 

[C] c [P] d . k F . K 

[A]“[B] b ' k BCV ' 

WHERE K IS A CONSTANT. 


c 

BUT WHAT IF OUR ASSUMPTION 

IS WRON6, ANP THOSE ARE NOT 

THE REAL RATES? NO PROBLEM' 

BY SOME MIRACLE, ALL INTER- 
MEPIATE STEPS CAN BE SHOWN 

1 

:q 

e [ 

D] 

\ 

d 

_ _ ■jr 

, TO lOMBIWE perfectly to * 

VALIPATE THE USE OF 

THE STOICHIOMETRIC 
COEFFICIENTS. THAT is, 

THERE REALLY IS A CONSTANT K, 

SUCH THAT AT EQUILIBRIUM; 

v_ 

i 

A] 

I a | 

[B] 

r ™ iv 

i b 


TO PUT IT ANOTHER WAY, NO MATTER WHERE THE REACTION STARTS OR HOW MUCH OF 
ANY INSREPlENT IS PRESENT AT ANY TIME, THE CONCENTRATIONS AT EQUILIBRIUM 
ALWAYS SATISFY THE EQUATION; 


icjwY „ K 

[A]“[B] b ' 

THIS FACT IS GA1.UEP THE 

law of mass 
action, 

ANP K IS THE REACTION’S 

equilibrium 

constant. 


SEE- THREE TIMES ON 
PASS... THINK THAT’S E NOUSH? / ^^ 



1 one^ 

OUSHr / V WO ) 





Example: Ionization of water 


CONSIPER H 2 0 H + + OH - . WATER 

MOLECULES OCCASIONALLY BREAK APART, 
ANP H + AMP OH' REACH AM EQUILIBRIUM 
CONCENTRATION. 

.£2. -"'>5 


A c ^ : * C ^r 


,V V 


PRECISE MEASUREMENT OF PURE WATER 
AT 25”C SHOWS [H + ] ANP [OH - ] TO BE 
ALMOST EXACTLY 10 -7 M - NOT MUCH.' 




THRCE-EYEP 



H* IONS ALWAYS ATTACH THEMSELVES TO A WATER 
MOLECULE TO MAKE H,0 + . 


WE PLU6- IN THOSE VALUES AMP 
CALCULATE THE EQUILIBRIUM CONSTANT. 


[H + ][OH - ] (10 -7 X10 -7 ) t0 -14 



MOW SUPPOSE 0.1 MOL OF HYDRO¬ 
CHLORIC ACIP, HCI, PISSOLVES IN A 
LITER OF WATER. HCI, A POLAR MOLECULE, 
ALMOST CO^?l^H PISSOCIATES INTO 
H + AMP Cl - IONS. SUPPEMLY, [H + ] RISES 
TO 0.1 M. THEN WHAT? 


ORR-RRI 


i» ; 4 P 


WHAT’S [H 2 0]? BEFORE PISSOCIATIOM, 
IT’S 55.6 M. 0 L OF WATER WEI6HS 
lOOOg; 1 MOL WATER WEI6-HS 19 93 
1OOO/10 = 55.6 J AFTER PISSOCIATIOM, 
IT’S 

55.6 - 0.0000001 
BARELY PIFFEREMT. SO WE CAN SAY 


** 


ANP WE 
USE THIS 






THEY PON’T CALL IT A CONSTANT FOR 
NOTHING WE IMMEPIATELY WRITE 

10" 14 = 55.6 K = [H + ][OH - ] 

= C0.1?[OH - ] 

SOLVING FOR [OH - ], 

[OH ] * 10 

THAT IS, THE APPEP H + IONS 6-OBBLEP 
UP EXACTLY ENOU&H OH' IONS TO MAIN¬ 
TAIN THE PROPUCT [H*][OH - ] AT A 
CONSTANT 1CT 14 . 








Le Chatelier’s Principle 


yOU CAN THINK OF EQUILIBRIUM A5 A 
BALANCE? 5EE5AW WITH REACTANT5 ON 
ONE 51 PE ANP PROPUCT5 ON THE OTHER. 
IN THE LA5T EXAMPLE, H 2 0 WA5 ON THE 
LEFT, OH" ANP H + ON THE RI6-HT. 


*V> 


(^for) 



IN THAT EXAMPLE, THE EQUILIBRIUM 
WA5 PI5TURBEP By APPIN6- H + TO THE 
RI6HT 51 PE. WHAT HAPPENS THEN? 




THE FRENCH CHEMI5T HENRY 19 £HA~ 
TELIER HA5 LEFT U5 A GENERAL PRIN¬ 
CIPLE FOR ANALyziN^ WHAT HAPPENS WHEN 
CHEMICAL EQUILIBRIUM 15 PI5TURBEP. 


FOR EXAMPLE, IF aA + LB — cC + dQ 
15 IN EQUILIBRIUM, THEN APPIN6 REAC¬ 
TANT A PRIVE5 THE REACTION TO THE 
RJ6»HT—CON5UMIN6 MORE A. 


When an external 
stress is applied to 
a system at equilib¬ 
rium, the process 
evolves in such a 
way as to reduce 
the stress. 








■©®t 



[OH'] FELL 5HARPLV, ANP EVERy 
OH' ION THAT PI5APPEAREP TOOK 
AN H + WITH IT, THEREBy LOWERING 
[H + ]. 


IN OUR EXAMPLE, APPIN& LOAP5 OF H + TO 
THE RI&HT-HANP 5IPE OF H 2 0 — H* + OH' 
PROVE THE REACTION TO THE LEFT. 















LE CHATELIER VERY CLEVERLy APPUEP HIS 
OWN PRINCIPLE TO THE SYNTHESIS OF 
AMMONIA, MH» A KEY INGREPIENT OF 
COUNTLESS PROPUCTS, FROM FERTILIZER 
TO EXPLOSIVE'S. 

U 2 (q) + W 2 (q) ** ZH^Cq) 

INCREASING PRESSURE, SAIP HIS PRIN¬ 
CIPLE, WILL PRIVE THE REACTION IM THE 
PIRECTION THAT REPUCES PRESSURE. 


H.JH, 


m 


THERE ARE FOUR MOLES OF GAS ON THE LEFT, BUT ONLy TWO ON THE RIGHT. By THE 
&AS LAW, PRESSURE IS P1RECTLY PROPORTIONAL TO THE NUMBER OF MOLES- SO 
PRESSURE IS RELIEVEP WHEN THE REACTION GOES IN THE PIRECTION OF FEWER 
MOLES, THAT IS, TO THE RIGHT. 


IN LE CHATELIER ATTEMPTEP THE SyNTHESIS 
AT A PRESSURE OF WO atm IN A STEEL "BOMB” 
HEATEP TO 600° C. UNFORTUNATELY AN AIR LEAK 
CAUSEP THE BOMB TO EXPLOPE... 


* A 



$ 




f \V 






...ANP THE CHEMIST SAVE 
UP THIS FERTILE LINE OF 
INVESTIGATION. 




r I CAN’T 
TAKE THE 
PRESSURE.., 





FIVE yEARS LATER, THE GERMAN 

FRITZ HABER succeepep where 

LE CHATELIER HAP FAJLEP, ANP 
EVER SINCE, AMMONIA SyNTHESIS 
HAS BEEN KNOWN AS THE 

Haber 

process. 



f { o * i • o 

V r v-’ 




T LET THE PI5COVERY OF THE 
AMMOMJA SyNTHESIS -&UIP TH ROUSH 
My HAN PS. IT WAS THE GREATEST 
BLUM PER OF My SCIENTIFIC CAREER.” 
-LE CHATELIER 


16B 







IN THIS CHAPTER, WE SAW HOW A NUMBER OF FACTORS AFFECTEP REACTION RATES; 


^ON/'ENTRATIOM: RAISING 
CONCENTRATION UPS THE RATE. 



O& © 


©® © 

~r ® 

©<$>o 




ATTIVATIOW ENER6Y: LOWERING it, 
BY MEANS OF A CATALyST, UPS THE RATE. 



TEMPERATURE: raisins. 
TEMPERATURE UPS THE RATE. 



WE ALSO SAW HOW A BUILPUP OF REAC¬ 
TION PRODUCTS COULP START A REVERSE 
REACTION THAT OVERTAKES THE FORWARP 
REACTION AT EQUILIBRIUM. 



IN THE NEXT CHAPTER, WE’LL EXPLORE SOME 6-REAT USES OF THE CONCEPT-ANP THE 
CONSTANT-OF EQUILIBRIUM, ANP IN THE CHAPTER AFTER THAT, WE’LL PI6 PEEP ANP 
PISCOVER WHAT EQUILIBRIUM REALLY MEANS. 



164 














Chapter 9 

Acid Basics 


A Cm, SOU R ANP A66-RE5- 
SIVE, ARE EVERYWHERE- IN 
SALAP PRESSING, RAJMWATER, 
CAR BATTERIES, 50FT PRINKS, 
ANP YOUR STOMACH. THEY 
£AN BURN, CORROPE, PI&E5T, 
OR APP A PLEASANT TAN& 

TO FOOP ANP PRINK... 

BASES, BITTER ANP SLIPPERY, 
MAY BE LESS FAMILIAR, BUT 
ARE EXACTLY AS COMMON AS 
A0P5. YOU’LL FINP THEM IN 
BEER, BUFFERIN, SOAP, BAKING 
SOPA, ANP PRAIN CLEANERS... 

AOP5 ANP BASES ARE SOME¬ 
TIMES USEFUL. OFTEN HARM¬ 
FUL, ANP ALWAYS A 6REAT 
OPPORTUNITY TO PLAY WITH 
EQUILIBRIUM CONSTANTS/ 



1A5 



A£(PS AMP BASES ARE INTIMATELY £ONNE<:T£P VIA PROTOWS, I.E., HYPRO&EN IOMS, H + , 



STRONG A£1P> WEAK 
CONJUGATE BASE, 
LOOSE PROTON 


WEAK A OP, STRONG 
£ON JU£ATE BASE* TOUT- 
ty BOUNl? PROTON 


1SS 















SOME CONJUGATE ACIP-8ASE PAIRS: 


ACIPS, STRONGEST 
TO WEAKEST 


BASES, WEAKEST 
TO STRONGEST 


SULFURIC H 2 S0 4 
HypROIOPIC, HI 
HyPR08R0MlC, HBr 
HyPROCHLORIC, HO 
NITRIC HMO, 

HypRONIUM, H,0 + 
BISULFATE, HS0 4 ' 
SULFUROUS, H 2 $0, 
PHOSPHORIC, H 3 P0 4 
HyPROFLUORIC, HF 
MITROUS HN0 2 
ACETIC (VINESAR), CH,C0 2 H 
CARBONIC H 2 C0 3 
AMMONIUM MH 4 + 
HypRocyANic, hcn 
BICARBONATE, UCOf 
WATER, H 2 0 


BISULFATE, H$0 4 ‘ 
IOPIPE, I~ 
BROMIPE, Br' 
CHLORIPE, CV 
NITRATE, NO ? “ 
WATER H 2 0 
SULFATE, $0/' 
BISULFfTE, H $0{ 


H.PO, 



’ 2 * '-'4 

FLUORIPE, F" 

NITRITE N0 2 ' 
ACETATE, CW^C0 2 
BICARBONATE, HC0 3 ' 
AMMONIA NH, 
CyANIPE, CKT 
CARBONATE, CO*' 
HyPROXlPE, OH' 




NOTE: BOTH Km ANP BABES £AN BE EITHER £HAR6EP OR NEUTRAU 


t & z —mil. v 





Acids and Bases in Water 


NOW WE WOULP 
like A NUMERICAL 
MEASURE OF an 

ACIP’S STRENGTH. 
THIS 15 EASIEST FOR 
ACIPS PISSOLVEP IN 
WATER. (MOST ACIPS 
WE ENCOUNTER IN 
THE WORLP ANP IN 
THE LAB ARE WATER 
SOLUBLE.; 



IMPORTANT SAFETY NOTE; 
ALWAYS APP A£IP TO 
WATER, NEVER VICE VERSA. 
WEAR 6LOVES WHEN 
HANPLIN6 STRON6 ACIPS. 



WHEN A STRONG ACIP PISSOLVES IN 
WATER, THE ACIP COMPLETELY IONIZES, 
OR ASSOCIATES. HYPROCHLORIC ACIP, 

FOR EXAMPLE, POES THIS; 

MCI —* M + + Ct' 



FOR CONVENIENCE, WE ASSIGN IT TO 
ONE OF THESE H 2 0 MOLECULES, ANP 
WE CALL THE CLUSTER A H/PRONIUM 
ION, H,0 + . IN SHORT, 

HCI + H 2 0 — H,0 + + Ct 



BUT THAT PROTON CAN’T FLOAT AROUNP 
FREELY ITS CHAR6E SOON PRAWS A 
CLUSTER OF WATER MOLECULES. 



m 









WE aN PESCRIBE THIS IN TERMS 
OF BASES, TOO. 

'a BASE IS JUST V^ve" ME.?) 
A HEAPLESS THAT... j 

< MW... j - S 


•vw 






WHAT’S TRUE OF HCl IS TRUE OF ALL 
STRONG A£IPS. THEIR £ONJU6ATES 
(MO,', ET£.) ARE ULTRA-WEAK BASES— 
WEAKER THAN WATER, WH1£H IS VERY WEAK/ 


INTEREST 
ANYONE IN A 
PROTON? 



\4 





THAT IS, pissolvep BASES REPUTE THE CONCEN¬ 
TRATION OF H,0\ 


YOU’RE BE£OMINg. A 
REAL RARITY... MUST BE 
1 BASES AROUNP... , 




TO SUM UP: IN AQUEOUS 
SOLUTION, ACIPS INCREASE 
[H,0 + ], ANP BASES PE- 
CREASE IT. [H,0*] IS A 

MEASURE OF A 

solution's Aciprry. 



wM 













PH 

MOW mu IS [H,0 + ]? LET 1 * REVIEW THE 
PISCUSSION ON PA6E 161 IN CHAPTER 9 • 
WATER ALWAYS IONIZES ITSELF A LITTLE'. 


A STRONG ACIP 6IVES AIL ITS 
PROTONS TO WATER TO MAKE 
H,0 + . FOR INSTANCE, A 1 M 
SOLUTION OF HNO, HAS 

[H ? 0 + ] = 1 M = 10° M 


H 2 0 + M 2 0 — H,0 + + OH- 


60 


AT EQUILIBRIUM, IN PURE WATER AT V?%, 
THE MOLAR CONCENTRATIONS OF H,0 + 
ANP OH' ARE BOTH 1.0 X 10' 7 M. 



THE EQUILIBRIUM CONSTANT FOR THIS 
REACTION IS 



[H,on[QH-] 

[H 2 0] 2 


BUT THE PENOMINATOR IS CONSTANT, 
OR NEARLV SO. ONLy ABOUT ONE 
WATER MOLECULE IN 556 , 000,000 
IONIZES/ THEREFORE THE NUMERATOR 
IS A CONSTANT TOO. WE CALL IT THE 

WATER CONSTANT. 


- CH,0 + ][0H-] 

* ao- 7 xio- 7 ) 


[0H-] PROPS TO K w /[H ? 0 + ] 
= 1C?’ 14 



ON THE OTHER HANP, A BASIC 
COMPOUNP LIKE NaOH PIS- 
SOCIATES FULLy IN WATER ANP 
RAISES [OH-]. [H,0 + ] FALLS 
ACC0RPIN6Ly. A 1 M SOLUTION 
OF NaOH HAS 

[0H-] = 1 


[H ? 0 + ] - 1C?- 14 . 




17 O 


FOR MOST PRACTICAL PURPOSES, 
THEN, [H ? 0 + ] FLUCTUATES 
BETWEEN t ANP 1 O' 4 . 



NOW WHEW CHEMIST* SEE 10 x , THEy 
OFTEN FJNP IT SIMPLER TO TALK 
ABOUT x, THE LOGARITHM. THEy PEFINE 

pH = -log [H,C> + ] 

pH stamps for Power of HypROGEN. 

pH RANGES APPROXIMATELy FROM O TO 
14. THE LOWER THE pH, THE MORE 
ACIPIC THE SOLUTION. FOR INSTANCE, A 
0.C71 M SOLUTION OF HCt HAS [H,0 + ] 
= .01 = 10'*, SO pH ^ 2. 



pH GOES POWN AS 
[H,0 + ] COES UP.' 



STUPIP MINUS 
SIGN... 





P 5% SULFURIC ACIP 

1 STOMACH ACIP 

2 LEMONS 
VINEGAR 

? APPLES, GRAPEFRUIT 
COCA-COLA, ORANGES 

4 TOMATOES, ACIPIFIEP LAKES 

5 COFFEE 
BREAP 
POTATOES 

6 NATURAL RIVERS 
MILK 

7 PURE WATER, SALIVA 
TEARS, SLOOP 

0 SEA WATER 
BAKING SOPA 


WHEN PEALING WITH BASES, IT CAN BE 
MORE CONVENIENT TO USE pOH. THIS 
IS PEFINEP AS 

pOH = -tog[OH'] 

ANP WE HAVE 

pH + pOH = M 


10 WATER IN MONO LAKE 
MILK OF MAGNESIA 


LIME WATER 


14 LyE, 4% SOPIUM HyPROXlPE 


f WE CAN MEASURE 
P H with INPICATOR 
CHEMI£AL£ that 
CHANGE COLOR AT 
PIFFERENT pH 
\ LEVELS. SEE? A 


% 


SORRy, IN THIS 
BOOK, I'M 
COLOR BLINPI 




Weak Ionization 


IN WATER, STRONG 
ACIPS IONIZE- WELL... 
STR0N6LY. WHEN 
HCl PISSOLVES, IT 
RELEASES VIRTUALLY 
ALL IT* HyPROVEN 
A* H + , ANP pH I* 
6IVEN PIRECTLY By 
HOW MUCH HCl I* 

IN SOLUTION. 


BUT A COMPLICATION ARISE* WITH H 2 *0 J( A STRONG ACJP 
WITH TWO PROTONS TO 6IVE. ONLy THE FIRST ONE 
IONIZES COMPLETELY 


H 2 S0 4 + H 2 0 — H 3 0 + + HS0 4 


kj ®"' klLk 


moT) ^S0 4 & A 

■aP' weaker acip, 

Ov WHICH PARTS 

WITH ITS 
PROTON LESS 
\ WILLINGLY 

iMd 


HOW PO WE SPECIFY THE “ACIPITY” OF WEAK ACIPS? THESE ACIPS IONIZE ONLY 
PARTWAY IN WATER. THAT IS, IF HB IS ANY WEAK ACIP IN AQUEOUS SOLUTION, 
IT SOMETIMES HANPS OFF ITS H + TO H 2 0, ANP SOMETIMES THE PROTON 
COMES BACK-. 


HB + H 2 0 


H,0 + + B~ 


( OH, BOY/ I 
FEEL AN 
EQUILIBRIUM 
CONSTANT 
COMIU6, ON!'/ 


X) 


■\ 

T / 

-l!'J / 



172 






HERE ARE K a VALDES FOR A FEW WEAK AO PS. A HI6H VALUE FOR K a MEANS A 
LAR6E NUMERATOR, THAT IS, A LOT OF IONS RELATIVE TO THE WON-IONIZEP 
SPECIES IN THE PENOMINATOR. THAT IS, HIGHER K a MEANS STRONGER ACID. 



ACIDS THAT SHEP MORE THAN ONE PROTON WILL HAVE MORE THAN ONE 
IONIZATION CONSTANT. FOR EXAMPLE, H 2 C0 ? , WHICH CAN SHEP TWO PROTONS, 
HAS K al FOR 



NOTE ALSO: IN WATER SOLUTION, SOME METAL 
IONS CAN ACT AS ACIDS. By 6RABBIN6- OH 
FROM WATER, THEy GENERATE H, 0 + . Fe*+ IS 
AN EXAMPLE: 

Fe 3+ + 2H 2 0 — FeOH 2+ + H,0 + 

FeOH 2+ + 2H 2 0 — FeCOHV + H ? 0+ 
Fe(0W) 2 + + 2H 2 0 — Fc(OH), + H,0 + 

ACID MINE PRAINA6E CONTAINS Fe* + . WHEN IT 
ENTERS A RIVER WITH HI6HER pH, IT PRECIPITATES 
OUT AS AN U6LY SLIME CALLED “yELLOW BOV* 


BRIN6 ME THE WORLD’S 
BI66EST BOX OF BAKINS 
-_-r SOPAI ,-> 



17 ? 






Example 

K a CAN BE U5EP TO FINP THE pH OF A WEAK ACIP SOLUTION. 


- -- —— \ 

VINEGAR IS A 5% SOLUTION OF ACETIC ACIP. THIS WORKS OUT TO ABOUT <7.0 MOL/L. 
WHAT IS THE pH OF AN 0.0 M SOLUTION OF CU,£0 2 H IN WATER? 

CH,£0 2 H — + H + (ABBREVIATING H,0* AS H + ) 

THE CONCENTRATION OF ACIP BEFORE IONIZATION IS 0.0 M. SUPPOSE IONIZATION 
REPUTES THIS VALUE By AN AMOUNT x. THEN WE CAN MAKE A TABLE: 


COUC. BEFORE IONIZATION 
CHANGE IN COnC. 
EQUILIBRIUM COHC. 


£H,C0 2 H 

CH,CO^ 

H + 

0.0 

0.0 

0.0 

-X 

X 

X 

0.0 -x 

X 

X 


ASSUMPTION 1: H + IONS 
FROM WATER ARE 
NE6U&1SUC COMPARER 
TO H + IONS FROM AOP. 


PLUG IN THE EQUILIBRIUM VALUES IN THE EQUATION FOR K a 




[ CH,fly] [H+] MOO 

[CH,£0 2 H] 


(0.0 - x) 


= 1.75 X 10- 5 (FROM THE TABLE) 


— » 1.75 X tO “ 5 
0.0 


x 2 * = (0,0X1.75)10'* * 14 x 10' 6 
x = (14) 1/2 x 10'* * 3.74 x 10~* 

BUT x s [H + ], SO 

pH = -log(?.74 xIO' 3 ) = 3 - log(3.74) * 3-057 

* 2.43 


ASSUMPTION 2: X IS 
SMALL 

COMPARED TO 0.0, SO 
WC CAN IGNORE IT (W 
me DENOMINATOR. 


ASSUMPTION 2 WAS 
JUSTIFIED, x RCALLy IS 
MUCH SMALLER THAN 0 . 9 . 


THI$ AL$0 TELl$ U* THE FRACTION OF 
MOLECULE* THAT IONIZE. 


[CH/O^J ?.74 X 10"* , „ 

- — ■■■ — . 5: 4./ 


[£H,£0 2 H] 


x 10 


0.0 


A LITTLE LESS THAN 5 MOLECULES IN A 
THOUSANP. 



TRY POING THE SAME CAL¬ 
CULATION WITH A 0.00 ft 
SOLUTION. MAKE THE SAME 
TWO SlMPLlFyiNG ASSUMP¬ 
TIONS. YOU 5H0ULP FlNP 
pH * 2.93, ANP ALSO THAT 
THE FRACTION OF IONIZEP 
MOLECULES SOES UP A$ CON¬ 
CENTRATION GOES POWN. 


174 



REACTION* DUCH AD 

Fe ?+ + 2H 2 0 — F eOU u + H,0* 

ARE CALLEP MyPROty^l6, OR 
WATER-DPLITTIN6. HERE IT IN¬ 
VOLVED AN ACIP, BUT IT’D ALDO 
VERy COMMON WITH BADED. 




WHEN A BADE B' (OTHER THAN 
OH'; ID PIDDOLVEP IN WATER, 
B“ TAXED H + FROM H,0 + . 



[H,0 + ] PROPD... [OH"] MUDT RIDE TO MAINTAIN X w 



THID CAN ONLy HAPPEN By DPLITTIND 
H 2 0, WHICH MAXED MORE H + .„ 



WHICH ID DOBBLEP UP By B ... ANP DO 
ON, UNTIL EQUILIBRIUM ID REACHEP. 



IN OTHER WORPD, B “ ^PROWES WATER ANP CAUDED A RIDE IN OH". 


H 2 0 + B' — MB + OH' 


ANP WE 6ET A NEW 
EQUILIBRIUM CONDTANT, 

THE BASE IONIZATION 
CONSTANT K b . 


[HB][OH] 
Kb “ [B ] 


179 










THE HIGHER THE Kp, THE STRONGER 

BA6E B 



THE BA6E. THI5 16 BECAU8EJ 

OH" 

HYOROXIOE 

55.6 

• HIGHER K* MEAN5 HIGHER 

6 2 ' 

5ULFIPE 

to 5 

[OH"], HENCE HIGHER pH. 

CO, 2 " 

CARBONATE 

2.0 XI O' 4 

• K b MEA5URE5 B’5 ABILITY TO 

NH, 

AMMONIA 

1.8 XlO“ 5 

TAKE A PROTON FROM H 2 0. 

B(OHV 

BORATE 

2.0X10~* 

• K b 15 INVER6E TO K a . IF HB 15 

HCO," 

BICARBONATE 

2.0X1 O' 0 

THE CONJUGATE ACIP, THEN 





onuKi y6nan 
‘ ’ Dpi xy\ 


. K.» 1 0' u 


Example. 


WHAT’5 THE pH OF A 0.15 M SOLUTION OF AMMONIA, NH,? CALCULATE A5 BEFORE, 
U5IN6-THE REACTION 

NH, + H 2 0 ^ NH/ + OH" 



NH, 

MM/ 

OH^ 

INITIAL- CON. 

0.15 

0.0 

0.0 

CHAN6E IN CON. 

-X 

X 

X 

EQUILIBRIUM CON. 

0,15-x 

X 

X 


A55UMPTIOM t: 
OH" FROM WATER 
15 ME6U6I8LE. 




0.15 


[NH/][OH] 

[NH,] 

* 1.8 X 10' 5 


(0.15 -x) 


= 1.8 XtO' 5 


x 2 - 2.7 X tO" 4 x - 1.64 X 10"’ 
[OH'] * 144 X 10~* 

P 0H = 3 - log (1.64) = 2.78 
pH » 14-pOH = 11.22 



A55UMPTIOM 2i X 15 
NCfrUftBLE 
PAREP TO 01* 


f NOTE' 
A55UMPTTON 
2 f5 A6AIH 
JU6TIREP JN 
THE EMP! 


176 





Neutralization and Salts 


IN WATER, ACIPS GENERATE H + ANP BASES GENERATE OH'. WHEN ACIPS ANP 
BASES COMBINE, THESE IONS NEUTRALIZE EACH OTHER. FOR EXAMPLE: 

UCKaq) + NaOWCaq) — Na + (aq) + Cl'Ca q) + M z O 

TWO NASTY CHEMICALS COMBINE TO MAKE AN ORPINARY SOLUTION OF TABLE 
SALT IN WATER. IF THE WATER EVAPORATES, ONLy SALT CRYSTALS REMAIN. 



THIS IS TYPICAL, SO TYPICAL, IN FACT, THAT IT’S THE PEFINITION OF A SALT: A 
SALT IS A SUBSTANCE FORMEP BY THE NEUTRALIZATION OF AN ACIP BY A BASE. 


^ANPBY^ 
f NEUTRALIZATION 
YOU MEAN...? 


I WAS AFRAIP YOU 
WERE SOI NS TO 
T ASK THAT... 



*gK2| 


BY NEUTRALIZE, WE MEAN THAT THE 
SALTS ARE MAPE FROM EQUIVALENT 
WEIGHTS OF ACIP ANP BASE. 


ANP gy EQUIVALENT 
WEI6HT, YOU MEAN...? 


>82 




SI6-H. 



AW EQUIVALENT WE16HT OF 

ACIP 15 THE AMOUNT THAT WOULP 

YIELPONE MOLE OF 
PROTON* IN WATER IF THE 
ACIP IONIZEP COMPLETELY. 

1 EQUIV HCt * 1 MOL 

BUT 

1 EQUIV H 2 50 4 * 05 MOL 

BECAUSE H 2 50 4 CAW 6IVE UP 
TWO PROTON5- SIMILARLY, 

1 EQUIV H 2 C0, * 05 MOL 



AN EQUIVALENT OF BA5E 15 THE 
AMOUNT THAT WOULP 6-IVE UP 
ONE MOLE OF OH' IF THE BA5E 
WERE TO IONIZE COMPLETELY. 50 

1 EQUIV NaOH = 1 MOL 
1 EQUIV Ca(0H) 2 * 05 MOL 
1 EPUIV NH 3 * 1 MOL 

BECAU5E 

K»V H 2 0 — NW/+OH' 

IF IT WERE TO IONIZE COMPLETELY. 




N EQUIVALENT5 OF ACIP ALWAY5 
NEUTRALIZE N EQUIVALENT5 
OF BA5E, BECAU5E THEY 
. MAKE EQUAL NUMBER5 
4 OF PR0T0N5 ANP 
, HYPROXIPE I0N5, 
RE5PECTIVELY. 




NOTE-. A 
“NEUTRALIZEP 1 
50LUTI0N MAY 
NOT BE NEUTRAL/ 
THAT 15, THE pH OF 
A 5ALT 50LUTI0N 
NEEP NOT BE 7. 


• 

•f «t 




BUT pH |* 7 

F WHENEVER A 
*TR0N6 acip 
NEUTRALIZE5 A 
*TR0N6 BA5E, A5 
WHEN NaOH NEUTRALIZE5 
H 2 50 4 TO MAKE Na 2 50 4 . 
THE 5ALT ION5 HAVE NO 
ACIP OR BA5IC EFFECT. 
THAT‘5 WHAT IT MEAN5 
THAT THEIR “PARENT’ ACIP 
ANP BA5E WERE 5TRON6. 



WHEW A STRONG ACIP NEUTRALIZES A WEAK BASE, THE SOLUTION WILL HAVE 
pH < 7. CONSIPER AMMONIUM NITRATE, NH 4 N0 3 , A COMMON INGREPIENT IN 
FERTILIZER. IT RESULTS FROM THE NEUTRALIZATION OF NH, (WEAK BASE) By 
HNO, (STRONG ACIP). 


HNO,(nq) + NH,(aq) NH 4 + (aq) + 

NO,' HAS NO BASIC EFFECT (BECAUSE 
HNO, IS STRONG), SO WE CAN IGNORE 
IT. IT’S A “BySTANPER ION.” BUT NH/ 

IS A WEAK ACIP THAT WILL PISSO- 
CIATE, WITH K a * 5.7 x 10~'°. 

NH/<aq) *=* NH,(aq) + H*(aq) 


NO, (aq) 



Example 

SUPPOSE THE CONCENTRATION OF NH 4 N0, IS 0.1 M. WHAT IS THE SOLUTION'S pH? 
WE MAKE THE USUAL TABLE ANP COMPUTATION • 



nh; 

NH, 

H + 


CONC. BEFORE IONIZATION 

0.1 

0.0 

0.0 

U^UAL ASSUMPTION It 
H + FROM WATGR IS 

CHANGE IN CONC. 

-X 

X 

X 

KlE&Lf&iBL£. 

EQUILIBRIUM CONC. 

0.1 - x 

X 

X 



AT EQUILIBRIUM, K a IS 


[H + ][NH,] 


^ 5,7 X 10 w 


[NH/] 

MAKING THE USUAL TWO ASSUMPTIONS, WE GET 
x 2 

— * 5.7 X 1 0~ w 

x 2 * 5.7 X 1 0~ n = 57 X 10-' 2 
x = [H + ] * 7.55 x 10 6 
pH = 6 - log (7.55) = 6 - 0.09 


USUAL ASSUMPTION 2. 

X IS MUZH LESS THAN 
0.1 ANP £AN BE I6NOREP. 







179 






SIMILARLY WHEW A STRON6 
BASE NEUTRALIZES A WEAK 
A£IP, THE RESULTING SALT 
SOLUTION WILL BE WEAKLy 
BASI£. FOR EXAMPLE, WHEN 
NaOH NEUTRALIZES CW^CO z W, 
Na + IS A “BySTANPER ION,” 
WHILE ACETATE, CW 3 C0 z , IS A 
WEAK BASE. WORK OUT FOR 
yOURSELF THE pH OF A 05 M 
SOLUTION OF Na£H ? C0 2 . USE 
Kt, OF CW 3 CO z * 5.7 X 1 O ao . 


yes... you work for a 

WHILE... LET ME FEEL LIKE 
TT A REAL SCIENTIST' 






f ANP WHEN ) 

c 

[ WEAK MEETS / 

[ 

S WEAK? ^ 

\ 






IF SALT RESULTS FROM 
NEUTRALIZATION OF 

pM 

STRON6 A£IP, STRONG BASE 

STRONG AOP, WEAK BASE 

WEAK AOP, STRONG BASE 

WEAK A£IP, WEAK BASE 

7 

<7 

>7 

<7 IF K a > K b 

7 IF K a » K b 
>7 IF K a < K, 

























Titration 


IS THE PROCESS OF NEUTRALIZING AN UNKNOWN SOLUTION BY GRIPPING 
("TITRATING") A KNOWN STRONG ACIP OR BASE INTO IT. 


IF, FOR EXAMPLE, THE UNKNOWN 
STUFF IS ACIP1C, WE TITRATE IT WITH 
A STRONG BASE, N«OH, OF KNOWN 
CONCENTRATION, SAy 05 M. 

pH SLOWLY RISES. AT THE 
ENDPOINT, WHEN THE ACIP IS 
NEUTRALIZED pH RISES RAPIPLy, 
SIGNALEP By A CHANGE IN COLOR 
OF AN INPICATOR CHEMICAL. 


IgMMittgg I 

■PUB mPgram] 

M 

B paw p 

whites 


«■* *- 


VOLUME APPEP 

NOW WE CAN FlNP HOW MANy 
EQUIVALENTS WERE IN THE ORIGINAL 
SOLUTION. SUPPOSE 50 ml OF 
UNKNOWN NEUTRALIZEP 9.3 ml OF 
NaOH. THEN OH" CONSUMEP WAS 

(.0093 LH0.5 mol/L) * 0.0047 mol. 

THERE MUST HAVE BEEN 0.0047 
EQUIVALENTS OF ACIP IN 50 mL OF 
UNKNOWN, OR 0.094 EQUIVALENTS 
60047 X 1000/50) IN A LITER. 


B CAUTION; THE pH NEEP NOT BE 7 AT THE 

ENPPOINT/ THE TITRATION MAy ENP WITH A 
SALT THAT HAS ACIPIC OR BASIC PROPERTIES. 


191 







WHEN SEVERAL IONS GET TOGETHER IN 
SOLUTION, INTERESTING THINGS HAPPEN... 

Solubility products 

SOME SALTS ARE VERy SOLUBLE, SOME HARPLV AT ALL. WHEN A SALT 
SOLUTION REACHES ITS MAXIMUM POSSIBLE CONCENTRATION, WE SAy IT IS 

5ATURATEP. ANy appep salt just falls to the bottom. 



(HERE A, THE CATION, HAS OXIPATION NUMBER ANP B, THE ANION, HAS 
OXlPATION NUMBER -n.) IONS ARE GOING INTO SOLUTION ANP FALLING OUT. 

AT LOW CONCENTRATION, THE FORWARP REACTION POMINATES. SATURATION IS 
THE EQUILIBRIUM STATE. 

V_V 


HERE IS THE EQUILIBRIUM CONSTANT. 

K _ [A' r ' f ] tv [B fl "] m 

eq ' own AJU 

THE PENOMINATOR CONTAINS WATER ANP THE 
UNPISSOLVEP SALT-BOTH ESSENTIALLT CONSTANT. 
SO WE IGNORE THEM AS USUAL ANP PEFlNE K 5p , 

THE toimujy PROPU£T; 

K sp = [A m+ ] n [B n- ] m 



m 





FOR EXAMPLE, A SATURATE!? SOLUTION OF CaCO, HAS A CALCIUM CONCENTRATION 
OF 6.76 X POSITIVE ANP NEGATIVE CHARGES HAVE TO BALANCE, 60 THE 

CARBONATE CONCENTRATION IS ALSO £76 X 1P“V THEN: 


K sp - [Ca 4+ ][C0/-] 

= (6.76 X 1C?' 5 ) 2 

» 4.57 X 1C?" 9 . (%%? 

BECAUSE CaCO, IS SO INSOLUBLE, WE CAN USE Ca 2+ IONS TO 
PRECIPITATE PI5SOLVEP CO, 2 ' FROM SOLUTfON. FOR INSTANCE, 
WHEN WE MAKE CAUSTIC LYE, NaOH: 

Ca(0H) 2 (aq) + Na 2 C0,(aq) — 2 NaOH + CaC0 3 Cs){ 


Ca 2+ ANP CO 2 ' WILL NOT STAy IN 
SOLUTION TOGETHER BEyONP 
WHAT THEIR SOLUBILITY PROPUCT 
ALLOWS. AS SOON AS THE APPEP 
Ca 2+ REACHES A LEVEL THAT MAKES 


IT POESNT 
TAKE MUCH, 
IN OTHER 
WORPS! 


[Ca 2+ ][CO, 2 '] * 4.57 X 10' 

CALCIUM CARBONATE BE6-INS TO 
PRECIPITATE OUT. 


r. iC 

'•&. AC; 
%j* v <$£ 

Asfc g 1 

' /il'' 

V ft* 



F«P0 4 

Fe,CPOA 

Fe(0H) 2 

Fe$ 

F®2^3 

AKOH), (AMORPH) 
A1P0, 

CaCO, U ALCITE? 

CoCO, (ARA60NrTE) 

CaMg(C0,) 2 

CaF 2 

Ca(0H) 2 

Ca,(P0,) 2 

CaSO/6/f^UM) 


1.26 X IP' 10 
1P' W 

3.26 X1P W 

5. PX1P" 10 
1P eB 
W** 

IP' 21 

4.6 X IP" 9 

6. PX1P"* 
2.PX1P*’ 7 
S.PXlP'" 
9.PX1P"* 
IP 24 


u 4 


Ba60„ 

PL Cl* 

Pt>(0H) 2 

PbSO, 

PbS 

MgNH„PO< 

MgCO, 

Mg(0H) 2 

Mn(0H) 2 

AqCI 

Ag 2 CrO, 

Ag*SO, 

ZnCOW z 

7x6 


1 0' w 
1.6 X IP’ 5 
9.PX1P*' 9 

1.6 X1P' 0 
IP' 27 

2.6 XlP' 1? 
IP' 5 

1.02 X IP' 11 

1.6 X1P' 1 * 
\0 AO 

1.6 XIP’ 12 
1.6 XIP' 5 
6.3 XlP' ,B 
3.26 XlP -22 


103 





K sp CAN HELP US FlNP THE EFFECT OF ONE ION ON 
ANOTHER’S SOLUBILITY. FOR INSTANCE, 


pH affects solubility. 


Example I. 

Ca(DW) 1 p- Ca 2t + 20H' 

K* P * [Ca 2+ ][OH'] 2 * 5.0 X 10' 6 

TAKE THE LOGARITHM OF BOTH SIPES= 

tog[Ca 2+ ] + 2log[OH'] = Gog 5) - 6 
= 0.7-S » -5.3 
log[Ca 2+ ]-2pOH = -5.3 

SUBSTITUTING pOM = 14 - pH, 

log [Ca 2+ ] = 22.7- 2 P H 


pH 



Ca(0H) 2 BECOMES MI&HLY 
SOLUBLE AT pH BELOW 12. 


Example 2. 


CaCO? — Ca 2+ + CO, 2 ' 

WHEN ACIP IS APPEP, CO, 2 ' TAKES UP 
H + TO MAKE HCO,' ANP H 2 C0,. HAVING 
THESE TWO PIFFERENT PROPUCTS COM¬ 
PLICATES THE MATH, BUT ON BALANCE, 
THE SITUATION IS POMINATEP BY= 

H + + CO 2 -— WCO{ 

BY LE CHATELIER'S PRINCIPLE, APPING 
H + PRIVES THIS EQUATION TO THE 
RIGHT ANP REMOVES CO, 2 '. TO 
MAINTAIN K* P , MORE CaCO, WILL 
PISSOLVE 




BOTH EXAMPLES SHOW HOW LOW-pH WATER TEN PS TO PISSOLVE MORE 
Ca 2 *. THIS IS A GENERAL PATTERN FOR METALS ANP EXPLAINS WHY 
AClPlFlEP LAKES OFTEN HAVE HIGH LEVELS OF PISSOLVEP TOXIC METALS, 


164 



Buffers 

WE CAN USE BASES’ PROTON- 
CAPTURING PROCLIVITIES TO 
MOPE RATE THE pH PROP 
CAUSEP By STRONG ACIPS. 



FOR EXAMPLE, START WITH A LITER OF .01 M 
SOLUTION OF SOPIUM ACETATE, NaCH,C0 2 . THIS 
IONIZES TO GENERATE .01 mot OF THE WEAK BASE 
ACETATE, CH 3 C0 2 ', CONJUGATE TO ACETIC ACIP. 



APP A LITER OF .01 M HCI, A STRONG 
ACIP. THE ACETATE ION 6RABS NEARLy 
ALL THE PROTONS OIVEN UP By HCI: 

CH 3 C0 2 ' + H + — CH 3 C0 2 H 



THE pH OF THE SOLUTION IS THAT OF A 
.005 M SOLUTION OF ACETIC ACIP. 
(CONCENTRATION IS HALVEP BECAUSE WE 
NOW HAVE TWO LITERS OF LIPUIPO 
THAT’S pH = 3.53. 



IF WE HAP APPEP THE HCI TO PURE WATER 
INSTEAP, THE pH WOULP HAVE PROPPEP TO 
2-3- THE ACETATE MOPERATEP THE 
AC I PITY OF THE WATER. 



WE SAy THAT THE ACETATE BUFFER* 
THE SOLUTION A6AINST ACIPS. 






WE MAy BE BOTHEREP By THE FACT THAT 
OUR BUFFER SOLUTION IS MOPERATELy 
ALKALINE, WITH A pH * S.B6. 



WE COULP LOWER THIS WITH A WEAK ACIP, 
BUT WE PONT WANT TO SIVE ANy PROTONS 
TO THE ACETATE IONS. THIS WOULP CUT 
THEIR BUFFERING ABILITy. 




so WE BRILLIANTLY USE ACETIC acip, 
CH,C0 2 H. ITS CONJUGATE BASE is ALREAPy 
ACETATE, SO IT WONT 6IVE UP PROTONS 
TO THE FREE ACETATE IN SOLUTION. 


AW CONJUGATE/ 
WANT A PROTON? 


NO MORE 
THAN yOU 
PO... 


IF WE MAKE A SOLUTION O.CA M IN 
ACETATE ANP JUST O.OOZ M IN ACETIC 
ACIP, THE pH WILL BE 5.5, NOT TOO 
BAP. (THE CALCULATION IS ON THE 
PACE AFTER NEXT,; 



EVEN BETTER, WE HAVE 
BUFFEREP AGAINST 
AC I PS ANP BASES 
SIMULTANEOUSLY' 

THE ACETIC ACIP WILL 
6IVE UP ITS H TO A 
STRONS BASE, WHILE THE 
ACETATE WILL TAKE 
PROTONS FROM STRON6 
ACIPS. pH WILL BE HELP 
WITHIN A LIMITEP RAN&E. 




ItfOjl. 




BASE BUFFER 


ACIP BUFFER 


IBS 







THIS IS THE TRICK WITH 
BUFFERS: USE AN ACIP AN 17 
BASE WITH A £OMMOM 
ION: COMBINE A WEAK 
ACM? MB WITH A SALT THAT 
IONIZES TO 6-IVE FREE B • 



I WISH I’P 
PATENTED 
THAT I PEA.' 



A BIT OF ARITHMETIC LETS 
US PREPICT THE pH OF 
BUFFERS, BOTH BEFORE 
ANP AFTER APPITION OF 
ACIPS OR BASES. WE START 
WITH THE WEAK ACIP HB. 



-- 

By PEFINITION, 

[M*][B~] 

a ' zm 

so 

CL1 

[M + ] ' [HB] 

TAKING L06 OF BOTH SIPES, 

L06 K a -L06- [H + ] = L06- C[B']/[HB]; 
WRITING pK a FOR -L0& K a , THIS BECOMES 

pH - pK a = log <[B~]/[HB]> 

WHICH IS CALLEP THE 

Henderson- 

Hasselbalch 

Equation. 



IN OUR BUFFER SOLUTION, THE SALT 
CONCENTRATION 6IVES [B'] ( ANP THE 
CONCENTRATION OF ACIP &IVES [HB]. K a 
WE KNOW, SO WE CAN SOLVE FOR pH. 

V_ 


197 



FOR EXAMPLE, OPPOSE A BUFFER 
SOLUTION CONSISTS OF t L OF 05 M 
HaO^COz ANP 0.1 M CH,C0 2 H. < a OF 
ACETIC ACIP IS 1.75 X 10'*, SO 

pK a * -logO.75 X 10 *) 

= 4.76 

THEN BY HENPERSON-HASSELBALCH, THE pH 
OF THE SOLUTION IS 

P H = P K a +log([B-]/[HB]> 

= 4,76 +■ \o^.05/0.1) 

= 4.76 +■ log 5 
= 4.76 + 0.70 * 

j£L£ 

IF A LITER OF 0.05 M HO IS APPEP, WE 
ASSUME THAT THE CW^CO^ BINPS WITH 
ESSENTIALLy ALL THE H + FROM HO: 

CU 3 C0 2 + H + ^ CH,C0 2 H 

THEN WE MAKE THE USUAL TABLE: 



ch,co 2 h 

ch,co; 

H + 

ORIO- CON. 

0.05 

0.25 

0.025 

CON. CHANOE 

0.025 

-0.025 

- 0.025 

EOUILIB. CON. 

0.075 

0.225 

0.0 



NOTE THAT CONCENTRATIONS ARE HALVEP, 
BECAUSE WE NOW HAVE TWO LITERS OF 
SOLUTION. THEN HENPERSON-HASSELBALCH 
SAys: 


pH = pK a + log 


[£H,co 2 ] 
[CH,C0 2 H] 


* 4.76 + log CO.225/0.075) 

* 4.76 + log 5 = 4.76 + 0.40 

* f t4 



SEE IF you CAN PO THE SAME 
CALCULATION IF WE HAP APPEP A 
LITER OF O.OA M NaOH INSTEAP 
OF THE HCt. 


108 




HENPERSON-HASSELBALCH CAN ALSO &UIPE US WHEN WE WANT TO APJUST 
THE pH OF A SYSTEM. 


FOR EXAMPLE, NH/ 15 MUCH LESS 
POISONOUS TO FISH THAN NH, 
BECAUSE THE UNCHAR6EP MOLECULE 
CAN PASS THROUGH CELL MEMBRANES 
EASILY ANP INTERFERE WITH METABO¬ 
LISM. HENPERSON-HA5SELBALCH SAyS 

log ([MH,]/[NH/P - pH- P K a 

IF, FOR EXAMPLE, WE WANT TO MAKE 
[NH,]/[NH/] LESS THAN ONE IN A 
THOU5ANP, I.E., ITS LOS- < -3, THEN 
pH MUST BE LOW ENOUGH THAT 

pH- P K a <-3 

SINCE pX a OF NH/ IS 9.3, ANy pH < 63 
WILL PO. 



SIMILARLY, WE APP HOC! TO SWIMMING POOLS TO KILL BACTERIA. THIS MILP 
ACIP PARTLY PISSOCIATES INTO H + ANP 00*. BUT NOW WE PO WANT IT TO 
BE POISONOUS, TO KILL BACTERIA! A6-AIN THE NONIONIZEP SPECIES H0C1 IS 
THE POISONOUS ONE, SO WE APJUST POOL pH TO LOWER [OCl"]/[HOO]. 



109 




WE COVERED A LOT IN THIS CHAPTER. WE MET AOPS ANP BASES, MEASURED 
THEIR STRENGTH, ANP SAW HOW THAT STRENGTH IS RELATED TO THEIR IONI¬ 
ZATION IN WATER. WE NEUTRALIZED TITRATED ANP LOOKED AT THE RESULTING 
SALTS. WE SAW HOW AO PS ANP BASES AFFECT A SALTS SOLUBILITY, ANP HOW 
BUFFERS ARE MADE By COMBINING. WEAK AO PS ANP SALTS. 



ANP NOW FOR SOMETHING 
COMPLETELY DIFFERENT... 








Chapter 10 

Chemical Thermodynamics 

A HARP, THEORETICAL CHAPTER THAT EXPLAINS 
WHY EVERYTHING HAPPENS 





WHEN YOU CONTEMPLATE 
THE UNIVERSE, yOU HAVE 
TO APMIT IT LOOKS PRETTy 
IMPROBABLE. THE SPECTACU¬ 
LAR SPIRALS OF GALAXIES... 
THE REGAL REGULARITY OF 
PIAMONPS... THE COMPEL¬ 
LING COMPLEXlTy OF LIFE... 
THE MURKy MySTERIES OF 
CHEMISTRy EXPLAINED WITH 
CARTOONS... 


• % 



IT’S ALL SO 

UNLIKELY/ 


rwi , 




191 



FOR EXAMPLE, A BRICK FLIES THROUGH 
A WIMPOW, AMP THE &LASS SHATTERS 
AMP 60ES FLYIM&. 



YOU MEVER SEE A BRICK HIT A PUPPLE 
OF 6LASS FRAGMENTS AMP CAUSE THEM 
TO FLY UP TO MAKE A WINPOW.' 



OR- SOME AIR IS LET IMTO A VACUUM 
CHAMBER AMP QUICKLY FILLS UP THE 
SPACE. 



YOU MEVER SEE ALL THE AIR IM A 
ROOM FLY IMTO THE CORMER. C OR IF 
YOU PO, YOU POMT LIVE TO TELL THE 
TALE.; 



THE REASOM IS THE 
SAME IM BOTH CASES'- 
THERE ARE MAMY, MAMY, 
MANY MORE WAYS FOR 
THIM6S TO FI.Y 

apart or $preap 

OUT THAM THERE ARE 
FOR THEM TO FLY 
TOGETHER AMP 6-ET 
COMCEMTRATEP. SPREAP- 
IM6 OUT IS VASTLY 
MORE PROBABLE. IT’S A 
GENERAL PRIMCIPLE OF 
THE UMJVERSE: 



192 



yOU MAY OBJECT TMAT PtCKlNS UP A BROOM AMP SWEEPING THE 6LASS SPLINTERS 
TOGETHER IS A CONCENTRATINS PROCESS. ANP yOU’P BE RISHT. 



BUT I REPLy THAT IN ORPER TO SWEEP, 
I HAVE TO MOVE My BOP* MOVING 
INVOLVES CHEMICAL REACTIONS THAT 
SPREAP HEAT INTO THE ENVIRONMENT. 



IN FACT, I COULPN’T HAVE MOVEP IN 
THE FIRST PLACE WITHOUT EATINS, ANP 
EATINS GENERATES WASTE THAT SETS 
SPREAP AROUNP TOO. 



THE FOOP I EAT ULTIMATELY PEPENPS ON SOLAR 
ENERSK WHICH SPREAPS A TERRIFIC AMOUNT OF 
MATTER ANP ENERSy INTO THE UNIVERSE. 



yOU HAVE TO LOOK AT THE 
BIS PICTURE/ ANy PROCESS 
THAT CONCENTRATES MATTER 
ANP/OR ENERSy IN A SySTEM 

is MORE THAN OFFSET 

By A SREATER AMOUNT OF 
SPREAPINS-OUT ELSEWHERE 
IN THE UNIVERSE. THE 

OVERALL EFFECT IN 
THE UNIVERSE AS A 
WHOLE IS TO SPREAP 
THIN6S OUT. 


19? 






IN CHEMICAL SYSTEMS WE CONSlPER TME SPREAPIN6-0UT OF ENERGY- 


IMAGINE A SYSTEM CONSISTING OF SOME 
TYPICALLY HUGE NUMBER OF MOLECULES. 
ANP LET US CONCENTRATE, FOR THE 
MOMENT, ON ONE OF THEM. 



AS WE SAW IN CHAPTER AT THIS SCALE 
ENERGY IS QUANTIZED. ONLY CERTAIN 
FlXEP ENERGY LEVELS ARE ALLOWED 



KINETIC ENERGY IS STORE? IN A 
MOLECULE IN THE FORM OF VIBRATION, 
ROTATION, ANP TRANSLATION fl.E., 
FLYING THROUGH SPACED 



ENERGY IS TAKEN ON OR GIVEN OFF IN 
PACKETS CALLEP QUANTA THAT JUMP 
THE MOLECULE FROM ONE ENERGY 
LEVEL TO ANOTHER. 



SO THIS IS THE PICTURE- EACH MOLECULE HAS ITS OWN ENERGY LEVELS... ANP WE 
THINK OF THE WHOLE SYSTEM AS ALL THESE ENERGY LEVELS TAKEN TOGETHER, WITH 
A VAST NUMBER OF QUANTA SPREAP OUT AMONG THEM IN SOME WAY. 














mswwmwwwwmwmmttuai 




mommmmmmimmmmmamm 










194 








































Entropy, S, 

MEASURES THE SPREAPIN6 OUT OF ENER&Y. IT CAN 
PE PGFINEP IN TERMS OF HEAT AND TEMPERATURE: 


START WITH A SYSTEM AT 
TEMPERATURE T (MEASURE? 
IN °fO ANP APP A SMALL 
AMOUNT OF HEAT q* 


SOMETIMES, q CAUSES A SMALL TEMPERATURE INCREASE 
AT. (q » EAT, WHERE C IS THE SYSTEM’S HEAT 
CAPACITY.; THE HEAT SPREAPS INTO HI6HER ENER&Y 
LEVELS. 



THE ENTROPY £HAN6E 

AS, IS 6IVEN BY 

AS = q/T 

WITH UNITS JOULES/ 0 ^. 


AT OTHER TIMES, q PROPUCES PHASE CHAN&E 
(MELTING, VAPORIZATION;. THEN TEMPERATURE 
REMAINS CONSTANT, BUT MOLECULAR MOTION 
BECOMES LESS CONSTRAINED ANP MORE LOW- 
ENER6Y LEVELS “OPEN UP.” THE HEAT SPREAPS 
INTO THESE ENER&Y LEVELS. 


AS THE FOLLOWING 
PIA6-RAMS SUREST, AS 
MEASURES THE EXTRA 
SPREADING-OUT OF 
HEAT IN THE SYSTEM 
RESULTING FROM THE 
APPITION OF q. 



‘PHY5JZI5T5 TELL U5 THAT q MU5T BE APPEP REVERSIBLY, THAT 15, THE HEAT ZAW BE SENT BA£K 
WITHOUT ANY EXTRA EXPEN5E OF ENERGY. THI5 15 PHY5l£ALiy IMP055IBLE, BUT an BE APPROXIMATELY 
AZHIEVEP BT APPIKI6 HEAT tW MAHy 5MALL 5TEP5. 


19? 
































IT IS WOW POSSIBLE TO 
CALCULATE THE ABSOLUTE 
ENTROPY OF Awy substance. 

THIS IS POME By APPIW6 UP 
ALL THE LITTLE ENTROPY 
INCREMENTS THAT PILE UP AS 
THE SUBSTANCE IS HEATEP IM 
SMALL STEPS FROM ABSOLUTE 
ZERO TO SOME CONVENIENT 
TEMPERATURE, USUALLy 290°K 
('ROOM TEMPERATURE, 25°a 


d> 





AT 290% WE WRITE $*, THE 

STANDARD absolute emtropy. 


FOR EXAMPLE, FIN PI MS THE STANPARP 
ABSOLUTE ENTROPY OF WATER INVOLVES 
THESE STEPS; 

£HILL a PERFECT ICE CRySTAL TO 
ABSOLUTE ZERO (NOT REALLy POSSIBLE, 
BUT CAM BE PONE IM THEORY;. 

SLOWLy APP SMALL INCREMENTS OF 
HEAT AMP APP UP ALL THE ENTROPy 
CHANGES FROM ZERO TO 273% THE 
MELTINS POINT (A TRICKY CALCULATION, 
BUT IT CAN BE POME?;. THIS AMOUMTS TO 

S 273 . = 47.04 J/mol% 

Melt the ice. water’s heat of fusiom 

IS 6020 J/MOL, ANP T= 273°, SO THE 
APPEP ENTROPY HERE IS 


6020 

273 


= 22.05 T/mol% 



Heat liquip water from 273® to 
ROOM TEMPERATURE ANP APP UP THE 
ENTROPY CHANGES. THEY TOTAL 

S 2W .-S 27r = 0.09 T/moHC 

APP the three subtotals for the 

ABSOLUTE STANDARD MOLAR 
ENTROPY OF WATER 

S°CwAT£R; = 47.04 T 22.05 f 0.09 
= 70» O JOULES/MOL°K 


t3 60 
^ •><? 
Si ao 
§ v> 
z 10 



TEMPERATURE T CO 


196 





SINCE PlFFERENT SUBSTANCES HAVE PlFFERENT HEAT CAPACITIES AMP HEATS OF 
FUSION AMP VAPORIZATION, PIFFEREMT AMOUNTS OF HEAT MUST BE APPEP TO 
RAISE THEIR TEMPERATURES AMP CHANGE THEIR STATES. IN OTHER WORPS, 
EVERy SUBSTANCE HAS ITS OWM CHARACTERISTIC STAMPARP ABSOLUTE ENTROPY 


STANPARP MO¬ 
LAR ENTROPY 

SUBSTANCE (J/X-MOL) 



fix'# (vis it**** 
wVNr £ 

- ■■ ' ♦ ‘ ■ 

£U&****fe*v:£*^*^ A**/*or*r*s& 

C (PIAMONp; 

2.4 

C (SRAPUrre; 

5.7 

Fe (iron; 

27.3 

Cu (copper; 

33.1 

Pt> (leap; 

64.0 



CaO 

39.7 

CaCO , 

92.2 

MaCl 

72.3 

MqCl 2 

095 

AIC1, 

167.2 



Ct2 W 22°n (sucrose; 

360.2 


ti>X T? V X >^ 

h 2 o a; 

70 

CH,OH {"methanol; 

126.0 

C 2 H,jOH cethanol; 

161 



H 2 0 (q) 

109 

CH 4 (methane; 

106 

CH,CH, (ethane; 

230 

H* 

131 

m 2 

191 

mh 3 

193 

0 2 

205 

C0 2 

213 

CH,OH (METHANOL, q) 

240 

C 2 H 5 0H (ETHANOL, q; 

203 


PIAMOMP’S AMAZIN&Ly LOW ENTROPV IS 
PUE TO ITS HARP, CRySTALLINE STRUCTURE, 
WHICH APMITS VERy LITTLE WI6SLE ROOM. 
GRAPHITE, MAPE OF SHEETS OF ATOMS, HAS 
MAMy MORE EMER&y LEVELS. 



LAR6ER MOLECULES HAVE HISHER EWTROPy 
THAN SMALLER MOLECULES: MORE PARTS TO 
MOVE. 



FOR ANy 6IVEN SUBSTANCE, 

S^SOLIP) < S°(LIQUIP) < S^CSAS). 



197 





















BECAUSE ENTROPY IS RELATED TO SUBSTANCES’ COMPOSITION ANP INTERNAL 
STRUCTURE, IT IS POSSIBLE FOR A SySTEM’S ENTROPY TO CHANGE WITHOUT AN 
APPITION OF HEAT. FOR EXAMPLE; 


the NUMBER of 

PARTICLES IN THE SYS¬ 
TEM RISES OR FALLS. 
MORE PARTICLES 
GENERALLY MEAN 
MORE ENERGY LEVELS, 
ANP SO ENTROPY 
GOES UP WITH THE 
NUMBER OF PARTICLES. 



THE SYSTEM EXPAND* OR £ONTRA£T* IT’S A WEIRP OUANTUM-MECHANICAL 
FACT (TRUST USD THAT MOLECULES GAIN ENERGY LEVELS WHEN THEY INHABIT 
A LARGER VOLUME. THEY’RE LIKE PANCERS WHO CAN SHOW OFF MORE MOVES 
WHEN THERE’S MORE SPACE ON THE FLOOR. 


THIS EFFECT EVEN HAS A 
FORMULA. IF A GAS EXPANPS 
AT CONSTANT TEMPERATURE, 
THEN 

AS = RlnCPp/P) 

WHERE ? 0 IS THE INITIAL 
PRESSURE, P IS THE FINAL 
PRESSURE, ANP R IS THE 
GAS CONSTANT. 





THE SYSTEM UNPERGOES A CHEMICAL REACTION 
A CHEMICAL REACTION CHANGES THE NUMBER OF 
PARTICLES ANP THEIR INTERNAL ARRANGEMENTS. THIS 
IS SO COMPLICATEP IT RESERVES ITS OWN SECTION. SO. 



198 








Entropy and Chemical Reactions 

THE ENTROPy TABLE IS OWE OF 
THE CHEMIST’S MOST POWERFUL 
TOOLS. IT ALLOWS US TO PREPICT 
WHETHER AMy REACTION WILL (?0 
FORWARP OR NOT fAT STAWPARP 

conpitions;. 


ENTROpy RULES THE UNIVERSE. WEVE ALRGAPy NOTEP THAT THE UNIVERSE 
60ES TOWARPS MORE PROBABLE, SPREAP-OUT STATES. EXPRESSEP IN TERMS 
OF ENTROPy, THIS BECOMES THE FAMOUS $E£ONP LAW OF TMERMO" 
DyNA/M£$, WHICH SAyS THAT ENTROpy MUST INCREASE. THAT IS, FOR ANy 
PROCESS WHATSOEVER, 




FROM THE STANPARP ENTROpy TABLE, WE CAN 
FINP THE ENTROPy CHANGE OF THE CHEMICALS 
INVOLVEP IN THE REACTION, WHAT WE WILL 
£ALL 

» S^propucts; - Surfactants; 

(S IS A “STATE FUNCTION,” I.E., IT PGPENPS 
ONLy ON THE INITIAL ANP FINAL STATE OF ' 
THE PROCESS ANP NOT ON THE STEPS IN 
BETWEEN.; 



199 


AS AM EXAMPLE, CONSIPER THE HABER PROCESS AT STANPARP CONPITIONS: SUPPOSE 
WE HAVE A MIXTURE OF N 2 , H 2 , AMP MU,... THE PARTIAL PRESSURE OF EACH 6AS 15 
1 ATM, AMP T = 298° K. POES THE REACTfON N 2 + 3H 2 —♦ 2NH 3 GO FORWARP? 


c 'N 

FIRST, COMPUTE THE EMTROpy CHANGE OF 

THE SYSTEM, I.E., THE MIXTURE OF 6ASES. 


- S^PROPUCTS) - ^(REACTANTS? 

= - 3$°CU 2 ) 



MOT 50 FA5T/ REMEMBER, IT’S THE ENTROPy 
OF THE ENTIRE UNIVERSE THAT MU5T 
RI5E, MOT THE EMTROPY OF THE 5Y5TEM. 
WE AL50 HAVE TO CALCULATE THE EMTROPY 
CHAN&E OF THE SURR0UNPIN6S. 

A^UNIVEIfSC " ^^y«TEM + ^^URROUNPIHfi« 

BUT 

HEAT AHAN5E OF 
SURR0UNPJNS5 


THI5 HEAT CHANGE 15 - AM WHERE AM 15 

the ENTMALPy £MAN6E of the reaction. 
-WE 5AW THI5 IN CHAPTER 5- 50 

A^univswc * AW ' ^M/T) 

k._> 


AM FOR THI5 REACTION CAN BE 
REAP FROM A TABLE OF EMTHALPIE5 
OF FORMATION. IN FACT, IT’5 TWICE 
AM f OF KIH, (BECAUSE THERE ARE 
TWO MOLE5 PROPUCEP* 


AM - 2AM F CNH,) 

= (2 MOLX-45.9 kJ/MOD 
= -91.6 kJ 


AM _ -91,600 J 
T ' 296 °K 


•309 J/°K 


THEN THE TOTAL ENTROPY 
CHANCE A550CIATEP WITH THI5 
REACTION 15 


AS sy * - CAM/T) 

* -196 J/ e K + 309 J/°K 
= 110 J/°K 


rr 15 POSITIVE! ALTHOUGH THE 
SySTEM’S EMTROPY FALL5, EM0U6H 
ENER6Y 15 5PREAP IN THE SUR¬ 
ROUNDINGS TO ALLOW THE 
REACTION TO GO FORWARP/ 




IT’5 ANAL06OUS TO SWEEPING UP BROKEN 5LA55. THE PROCE55 
C0NCEMTRATE5 ENER5Y WITHIN THE 5Y5TEM, BUT THE RE5T OF THE 
UMIVER5E HA5 TO 5PREAP OUT ENER GY TO ENABLE IT TO HAPPEN. 


2 00 




THE SAME APPROACH APPLIES TO ANY REAC 
TION AT CONSTANT P AMP T. IF A// IS THE 
REACTION’S ENTHALPY THEN 

A£$URROUNPIN64 ' 'A/y/T. 

THE TOTAL ENTROPY IS v 

^^UNIVER^E * ^5Y5TEM + ^^^URROUMPIM65 

WHICH BECOMES 

^UNIVERSE = ' (A/V/T) 

this IS THE TOTAL 5PREAPIN6- OF ENERGY 

IW THE UNIVERSE AS A RESULT OF THE REACTION. 


By THE DEFINITION OF ENTROPY THE TOTAL AMOUNT OF ENERGY SPREAD IS 
TAS UN1VEWC . WE SAy THE REACTION HAS A FREE EWER6Y £MAN6E OF 
'TAS UMlvCR5e . THIS LAST EXPRESSION IS CALLED A6, AFTER THE AMERICAN 
CHEMIST J. WILLARD &IBBS (1939-1903). MULTIPLYING THE LAST EQUATION By -T 
GIVES THIS VALUABLE EXPRESSION FOR A6: 

AG = AH -TAS system 




yOU MIGHT CALL IT THE 
SYSTEM’S ENTROPY 
FIGHTING WITH THE 
ENTHALPY! 


GIBBS 


AG REPRESENTS THE NET AMOUNT OF ENERGY THAT CAN POTENTIALLY BE 
CAPTURE? AS WORK WHEN IT SPREAPS OUT. IN FACT, YOU CAN THINK OF THE 
GIBBS FUNCTION AS THE MAXIMUM AMOUMT OF WORK THAT CAN BE 
PONE BY THE REACTION. 



AS WE’LL SEE NEXT 


CHAPTER, FREE ENERGY 


CAN BE HARNESSEP TO 


PUSH ELECTRONS 

$WT 

THROUGH A WIRE. 




rrr-zxr 






YOU CAN THINK OF THE TWO TERMS IN THE 6-1 BBS FUNCTION GRAPHICALLY'. 


AW IS THE CHANGE 
IN THE GROUNP 
STATE—THE LOWEST 
ENERGY STATE- 
BETWEEN REACTANTS 
ANP PROPUCTS. THIS 
REFLECTS CHANGES 
IN THE STRENGTH OF 
CHEMICAL BON PS. 



A H>0 

MEANS 

PROPUCTS’ 

GROUNP 

STATE IS 

HIGHER. 


REACTANTS PROPUCTS 


-TAS, THE ENERGY 
ASSOCIATE? WITH THE 
SYSTEM’S ENTROPY 
CHANGE, REFLECTS 
CHANGES OF K.E. STATES 
BETWEEN REACTANTS 
ANP PROPUCTS, I.E., 
PIFFERENCES OF SIZE, 
SHAPE, ARRANGEMENT 
OF MOLECULES, ETC. 


assppps 

? ♦« 

f * ♦ rup *'.'■*. 

XVFZY*'**''*** *'*''• 

:x -J 



AS > 0 MEANS 
PROPUCTS HAVE 
MORE ENERGY 
LEVELS TO FILL. 


REACTANTS 


PROPUCTS 











WHEN IS A REACTION SPONTANEOUS? IT HELPS TO DISTINGUISH AMONG FOUR CASES, 
DEPENDING ON THE SIGNS OF AW AND AS (MEANING AS WTCM ). 


AH < P EXOTHERMIC 

AS > 0 SYSTEM ENTROPY INCREASES 

AG IS ALWAYS NEGATIVE. THE REACTfON 
IS SPONTANEOUS AT ANY TEMPERATURE 


TAS 



TEMPERATURE 



— AW 


ENERGY ALWAYS 
SPREADS TO 
MORE LEVELS. 


REACTANTS 


PRODUCTS 


AH > 0 ENDOTHERMIC 

AS < 0 SYSTEM ENTROPY DECREASES 

AG IS ALWAYS POSITIVE. THE REACTION IS 
NEVER SPONTANEOUS. THE REVERSE REACTION 
IS ALWAYS SPONTANEOUS. 




ENERGY NEVER 
“UNSPREAPS' TO 
FEWER LEVELS. 


REACTANTS 


PRODUCTS 


AH > 0 ENDOTHERMIC 

AS > O SYSTEM ENTROPY INCREASES 

AG < 0 WHEN AH < TAS. TAS, THE 
ENERGY SPREAD OUT BY THE SYSTEM’S 
ENTROPY RISE, MUST EXCEED AH, THE 
ENERGY DRAWN FROM THE SURROUNDIN&S. 

SPONTANEOUS FOR T > AH/AS 


AH <0 EXOTHERMIC 

AS <0 SYSTEM ENTROPY DECREASES 

TAS IS THE ENERGY LOST BECAUSE OF THE 
SYSTEM'S ENTROPY PROP. AG < 0 ONLY WHEN 
THE REACTION RELEASES EVEN MORE ENERGY, 
I E-, AH < TAS, OR WHEN T < AH/AS. 

SPONTANEOUS ONLY FOR LOW T. 




T 

AW 




LOW T, NO 


HIGH T, YES 


LOW T, YES 


HIGH T, NO 




































IN OTHER WORPS, THE COMPONENTS OF THE SlBBS FUNCTION, LM ANP TAS, 
PREPICT THE TEMPERATURE RAN6E WITHIN WHICH A REACTION WILL TAKE PLACE 
SPONTANEOUSLy— PROVIPEP THE REACTION HAPPENS AT CONSTANT T ANP P. 


A REASONABLE 
ASSUMPTION— 
SOMETIMES' ) 












TO APPLy 6-IBBS FREE EMER6Y, WE BE6IN WITH A REACTION AT STANPARP 
CONPITIONS, ANP THEN TWEAK THE 6-IBB5 FUNCTION TO REFLECT CHANGES 
IN PARTIAL PRESSURES OR CONCENTRATIONS. 


EVERy SUBSTANCE HAS A 

STANPARP FREE ENERGY 
OF FORMATION (,%. THIS 15 
THE FREE ENER&y CHANGE WHEN 
THE SUBSTANCE IS MAPE FROM 
ITS CONSTITUENT ELEMENTS AT 
STANPARP CONPITIONS. IN 
OTHER WORPS, IT IS A6 OF 

ELEMENTS —* SUBSTANCE 

NATURALLY CHEMISTS HAVE 
COMPILEP VAST TABLES OF 
THESE. HERE IS A LITTLE ONE. 


SUBSTANCE 

6p(kJ /MOD 

C0 2 (g) 

-394.37 

NH,(q) 

-16.4 

N 2 (q) 

0 

H 2 Cq) 

0 

CaO (s) 

-604.1 

H 2 0 (1) 

-137.19 

H 2 0 (q) 

-1193 9 

0 2 (q) 

0 

H + (aq) 

0 

OH' (aq) 

-197.19 


ONE CAN SHOW CAS WITH ENTHALPy OF FORMATIONS THAT AW REACTION 
TAKING PLACE AT STANPARP CONPITIONS HAS free ENER&y EQUAL to 
THE PIFFERENCE BETWEEN THE STANPARP FREE ENERGy OF FORMATION OF THE 
PROPUCTS ANP THE STANPARP FREE ENER&y OF FORMATION OF THE REACTANTS: 


AG = G£(PROPUCTS) - G* (REACTANTS) 



W<7 







LET'S WRITE L(?° TO INDICATE THAT OUR REACTION TAKES PLACE AT STANDARD CONDITIONS 
(T*29TK, p-t ATM;. WHAT HAPPENS WHEN WE (CHANGE PRESSURE? 


WHEN A 6AS CHANGES PRESSURE AT CON¬ 
STANT T FROM AN INITIAL PRESSURE ? Q 
TO A FINAL PRESSURE P, THE ENTROPy 
CHANGE OBEYS THIS EQUATION 
(OFFERED WITHOUT PROOF—SORRY/;-- 


AS = R InCP^/P) 


(R THE 6AS 
CONSTANT) 


REMEMBER, 

EXPANSION 

INCREASES 

ENTROPY/ 


THE PRESSURE CHANGE INVOLVES NO HEAT 
TRANSFER; AW = P. SO THIS PROCESS (I-E-, 

THE PRESSURE CHANGE) HAS FREE ENERGY; 

6 f - 6° p = AW-TAS = -TAS = -RTlnCP^/P) 

SO 

6- f * 6* - RTln(P 0 /P) = + RTlnCP/pp 

= + RTlnP 

BECAUSE ?„ = 1 AT STANPARP CONDITIONS). 




EXCELLENT/ NOW LET P VARY ANP CONSIPER 
REACTIONS AT CONSTANT T = 298°K. THEN 

A6 = (^(PRODUCTS) - 6 F (REACTANTS; 

NOW LOOK AT ANY HYPOTHETICAL 
REACTION WITH BALANCEP EQUATION | 

aA + fc>8 s=» cC + ctP ^ 

ANP ASSUME A, B, C, ANP P ARE ALL SASES 
THAT REMAIN MIXEP TOGETHER, WITH PAR¬ 
TIAL PRESSURES P A , P B , P t , AND P p . THEN 




POES 

LOOK 


ANYTHING 

FAMILIAR? 


A6 = (^(PRODUCTS) - & F (REACTANTS) 

= 6^ (PROP) - (?% (REA Q + RT(clnP £ + d tnP p - a lnP A - b lrP B ? 


- LG° + RTln / Pc Pp ) 

lP A a P ? b / 






Equilibrium Again 


p c p a 

p a p 
r A r B 

15 CALLEP THE REACTION 
QUOTIENT. <9 15 5MALL 
WHEW PROPUCTS ARE SCARCE 
COMPAREP TO REACTANTS, 

AMP LAR&E WHEN VICE VERSA. 
IF A, 0, C, ANP P ARE 
PI5SOLVEP CHEMICALS, WE 
CAN ALSO WRITE 


Q = 


icym* 

[A]“[B] 1 


ANP IT REMAINS TRUE THAT 

LG = LG° + RTlnQ 

NOTE THAT LG < 0 IF <9 15 
SMALL EN0U6H, ANP LG > 0 
IF <9 15 LARSE ENOU6H, THAT 
15, IF LOT5 OF C ANP P ARE 
PRESENT. 


1 TRANSLATION; / 

WHEN Q 15 5MALL, L 
THE REACTION 6065 B 
FORWARP/ WHEN Q W ( 
15 LAR6E, THE ] ' 

REACTION REVERSES! * -- 

V---THANK 

1/ W you. 


EQUILIBRIUM OCCURS WHEN LG - 0, OR 
RTlnQ ^ - LG° 


q = e (-LG*/ RT? 



© 


THI5 15 A 5EC0NP PERIVATION OF THE 
EQUILIBRIUM C0N5TANT/ IT SAYS THAT AT 
EQUILIBRIUM, THERE 15 A C0N5TANT K eq 
5UCH THAT 

[OTP]’ 1 _ K 

[A]“[B] b " ” 


ANP 5lMILARLy FOR PARTIAL PRE55URE5. 
EVEN BETTER, NOW WE CAN CALCULATE 
K eq FROM 5TANPARP FREE EWER6IE5 OF 
FORMATION, WITHOUT EVER RUNNIN6 THE 
REACTION/ 


K ‘ - e 

eq 


C-LGVRT) 


(ANP REMEMBER, IN THIS EQUATION 
T * 299°K.) 


107 



JU5T FOR FUM, LET’5 5EE IF WE £AN 
aU^ULATE THE IONIZATION £ON5TANT OF 
WATER IN TWI5 WAY. 

M z O CD — H + (aq) + OH'Caq) 

<& p F CPROPU4T5;> - (REA4TANT5) 
FROM THE TABLE; 

&° f (W 2 0 CO) * -237.16 IcT/mol 
^(OH^aq); * -157.29 kJ/mol 
6>%(^Caq)) - O 
50 

-157.29 - (-237.10) = 79.69 kj/mol 
* 79,694? J/mol 
% s e (-A6°/RT? 

q _ c C-79,090)/(0.3tS4X290> 

» e -”- 25 
- 9.9 X lO' 15 

= It?' 14 OR CL05E EM0U6H' 








Chapter 11 

Electrochemistry 

v s ^ IN WHIOI LI&HTS BLAZE ANP BELLS RIN6, // 
V UNTIL TME BATTER/ RUNS POWN... / 



© 

© 



© 

© 

0 

© 




/ 


© e 

0 © © © 


© 



In TME 

LAST CHAPTER, 
WHEN WE SAIP 
ENER6-y «3ULP x 
BE EXTRA£TEP 
FROM cwmcki 
REACTIONS, WE 
SEZRETLy MAP A 
CERTAIN KINP OF 
ENER^y IN MINP: 

ELECTRICAL 

ENER^y. 


e ®©o® 


© o 
© 


REACTIONS THAT MOVE ELECTRONS AROUNP, yOU MAy RECALL FROM 
CHAPTER 4, ARE £ALLEP REPOX REACTIONS REPOX REACTIONS 
TRANSFER ELECTRONS FROM ONE ATOM TO ANOTHER, ANP WE 
WOULP LIKE TO MAKE THAT TRANSFER HAPPEN By A ROUNPABOUT 
PATH, PASSING THROUGH A LJ6HT BULB, FOR INSTANCE/ 


© 

© 

© 
© 
© 


\ 



209 


© © 



Redox Redux 


REPOX 15 5H0RT FOR REPUmON-OXlPATlON. IN A REPOX REACTION, 
TME ATOM PONATIN6- THE ELECTRONS 15 OXIPIZEP, ANP THE ONE A££EPTIN6 
THEM 15 REPU^EP. 



an atom’5 OXIPATION NUMBER is the 

NUMBER OF EXZE55 CHAR6E5 PUE TO THE 
U055 OR 5AIN OF EL.EZTRON5. FOR IN5TAN£E 


/ 

-4 


CW A + 


\ 

+1 


20 , 

4 

I 

O 


— CO x + 2W 2 0 


/ 


+4 


\ 

-2 


/ 

+1 


\ 

-2 



A REPUZTION ALWAY5 
REPUCE5 THE 
OXIPATION NUMBER! 


ON THE LEFT 51PE OF THE EQUATION, OXy&£N’5 NUMBER 15 ZERO. EAZH OXYOEN 
ATOM TAKES ON TWO ELEOTRON5 ANP 50 15 REPU^EP TO -2. THE5E EI&HT 
ELE0TRON5 ^2 X 4) £OME FROM CARBON ANP OXIPIZE IT FROM -4 TO +4. 
HYPRO&EN 15 NEITHER OXIPIZEP NOR REPU^EP. 







IF A me BAR 15 IMMERSEP IN A SOLUTION OF COPPER 0D SULFATE,* CuS0 4 , 
THE mC METAL SLOWLY OXlPJZES AMP PISS0LVE5, WHILE COPPER IONS PI CK 
UP ELECTRONS ANP FALL OUT OF SOLUTION AS PURE METALLIC COPPER. 




B in this reaction, electrons move straight from one 

ATOM OR ION TO ANOTHER. BUT NOW WE PO SOMETHING 
CLEVER; SEPARATE THE OXIPATION FROM THE REPLETION, 
BUT 60HHUT THE REACTION SITES BY A £ONPU£TIN6 WIRE. 

*JT* BLUE, W THE WAyJ 


211 






A ZIN C BAR IS IMMERSE? IN A Itf AQUEOUS SOLUTION OF ZnS0 4 . COPPER IS 
IMMERSE? IN A 1M SOLUTION OF CuS0 4 . THE TWO BARS—OR 5LGCTRO PE6— 
ARE £ONNE£T£P By A WIRE. ELECTRONS WILL STILL NOT FLOW, HOWEVER, 
SlN£E THEy WOULP CREATE A £HAR£E IMBALANCE. 


TO MAINTAIN 

<:har&e balance, 

IONS MUST BE 
ALLOWEP TO 
FLOW FROM ONE 
SOLUTION TO 
THE OTHER. 


IF WE MAKE A PATH FOR IONS, ELECTRONS WILL MOVE THROUGH THE WIRE. IT’S 
THE ONLy WAY THEy £AN 6£T FROM Zn TO Cu 2+ I DISSOLVE? U 1 * IS REPUZEP 
AN? PEPOSITEP ON THE COPPER ELEOTROPE. Zn IS OXlPIZEP ANP PISSOLVES. 
SO/' MIGRATES TOWARP THE ZIN( ELKTROPE. [Zn 2+ ] RISES ANP [Cu 2t ] FALLS. 


THE ELECTRON 
SINK, OR 

CATHODE, 

ATTRACTS 
POSITIVELy 
(HAR6-EP 
NATIONS 
(HERE, MAINLy 
Cu 2+ BUT 
SOME Zn 2+ 
TOO). 




212 








WHY PO THE ELECTRONS FLOW? BECAUSE FOR THEM IT'S LIKE FALLING 
POWNHILLI THE ELECTRONS HAVE A LOWER POTENTIAL ENERGY AT 
THE £ATHOPE. TO PUT IT ANOTHER WAy, ENERGY WOULP HAVE TO BE APPEP 
FROM OUTSIPE TO PUSH THE ELECTRONS "UPHILL” FROM £ATHOPE TO ANOPE. 



© 


MOTE: THIS IS AN ANALOGY 
ONLy.' ELECTRONS ARE NOT 
LITERALLy FLOWING POWNHILLI 

just LOSIN6 ENERGY/ 


THE REACTION'S "PUSH^THE ENERGY PROP PER CHAR6E-IS CALLEP THE VOLTA6E 
OR ELECTRIC POTENTIAL, AE. its units are VOLTS, about which 

MORE SOON. A METER ON THE WIRE SHOWS THAT THE COPPER-ZINC REACTION 
GENERATES 1.1 VOLTS. WE CAN HARNESS THIS "ELECTRON SPILLWAY” WITH A 
LI&HT BULB OR MOTOR OR BELL. THE ELECTRONS PO WORK. 



EUREKA/ 

EUREKA/ 

EUREKA/ 


THIS S£TUP IS CALLEP 

A VOLTAIC CELL, or 

LOOSELY SPEAKING-, AN 

ELECTRIC BATTERY.* 


*STRI£TLy SPEAKING., A BATTERy (CONSISTS OF SEVERAL (CELLS WIREP IN SERIES. 



BECAUSE A CHEMICAL CELL PHYSICALLY SEPARATES REPUCTION AMP OXIPATION, 
CHEMISTS LIKE TO THINK IM TERMS OF SEPARATE HALF-REACTIONS THAT 
PESCRIBE THE ELECTRON TRANSFERS. IN THE ZINC-COPPER CELL, THE HALF- 
REACTIONS ARE: 


OXIPATION: Zn — Zn 2+ + 2a 
REPUCTION: Cu 2+ + 2a ^ Cu 


WHEN HALF-REACTIONS ARE APPEP 
TOGETHER, ELECTRONS APPEAR ON 
BOTH SIPES ANP CAN BE CANCELLEP: 

Zri + Cu 2+ + ifc ’ — Zn 2+ + Cu + 'fc 



MORE (SIMPLE} REPOX REACTIONS IN SOLUTION ANP THEIR HALF REACTIONS: 


WHEN IRON FILINGS ARE APPEP TO 
ACIP, THEY REPUCE H + , ANP HYPR06EN 
&AS IS EVOLVEP. (TTHIS IS HOW 
RECREATIONAL HYPROG-EN USERS 
MAPS IT IN THE 10TH CENTURY/} 



2H + (aq) + F a(s) —► Fe 2+ (aq) + H 2 (q) 

HALF-REACTIONS: 

REPUCTION: 2H + + 2a — H 2 
OXlPATION: F a —> Fe 2+ +■ 2a 



214 







LISTING AC FOR EVERY RGPOX 
REACTION WOULP BE TEPIOUS, 
BUT IT TURNS OUT WE SAN 
ASSIGN VOLTAGES E ox ANP E Rep 
TO TME HALF-REACTIONS ANP 
APP THEM TOGETHER. 

AE ~ + ^REP 

THE VOLTAGE OF ANY FULL REAC¬ 
TION IS FOUNP BY APPING UP ITS 
HALF-REACTION POTENTIALS. MUCH 
MORE CONVENIENT? 


NO CHEMIST IS 
IMMUNE TO THE 
BEAUTY OF AN 
IMPROVER 
BOOKKEEPING 
\ SCHEME... 



SO, FOR INSTANCE, 

E ox (Zn — Za 2+ + tel = 0.7CV 
E R£P (Cu 2+ + 2e — Cu) = 0.94V 

AE OF THE WHOLE REACTION IS 
0.77 + 0.94 * 1.10 V 


BUT WHERE PIP THESE 
NUMBERS COME FROM, 
—r ANYWAY? -- 



WE CAN THINK OF THESE AS THE 
OXIPIZEP SPECIES’ TENPENCY TO GIVE 
ELECTRONS AWAY ANP THE REPUCEP 
SPECIES’ URGE TO PICK THEM UP. 


m, 


GIVE AWAY TO 
WHOM? PICK UP 
FROM WHERE? 




HOW CAN WE ASSI&N VOLTA6ES TO HALF-REACTIONS WHEN HALF-REACTIONS NEVER 
HAPPEN ALONE? 


THIS IS HOW: FIRST, SINCE 
VOLTAGE PEPENPS ON 
CONCENTRATION, PRESSURE, 
ANP TEMPERATURE, WE 
ASSUME STANPARP 
CONPITIONS: T = 298% 
P = 1 ATM, CONCENTRA¬ 
TION • 1 M. WE CALL OUR 
HALF-REACTION VOLTA6E A 

STANPARP REPUCTION 
POTENTIAL, E or 

SIMPLY 



( IS THERE ANYTHING THAT 
POESNT PEPENP ON 
TEMPERATURE, PRESSURE, 
ANP CONCENTRATION? 


IT WILL BE A REPUCTION POTENTIAL, BECAUSE FOR CONVE¬ 
NIENCE WE WRITE ALL HALF-REACTIONS AS RE- 
PUCTIONS. IF A REACTION RUNS LEFT TO RI(9HT, IT'S A 
REPUCTION} IF RI6-HT TO LEFT, IT’S AN OXlPATION, ANP 



FINALLY, WE MEASURE 
ALL REPUCTION 
POTENTIALS A6-AINST 
THAT OF HyPROfrEN, 
I.E., THE REPUCTION 
2H* + 2e' —♦ H 2 , 
WHICH IS ASSI6NEP 
A VALUE B° =0. 


THE HYPROSEN REPUCTION IS PONE BY BUBBLING H 2 AT ONE ATM OVER A CATALYST, 
PLATINUM PIOXlPE, Pt0 2 , INTO AN ACIP AT pH=0 CAT STANPARP CONPITIONS, 
[H + ] * t m;. 



21S 





*OME HALF-REACTION* OXlPIZE H 2 (£.(&., Cu 2+ + 2c' — CuA WHILE OTHER* 
(Fe 2+ + 2e~ — Fe; REPUCE H + . ANYTHING THAT REPUCE* H + WILL HAVE A 

NEGATIVE REPICTON POTENTIAL. 


HALF-REACTION 

e°cv; 

HALF-REACTION 

b° on 

U* + — * U 

-305 

Ni 2 * + 2e' _ Ni 

-0.2* 

tc* + a — K 

-2.93 

*n 2+ + 2e —* *n 

-0.14 

Ba 2 * + 2e — Ba 

-2.92 

Pb 2t + 2e Pb 

-0.13 

*r 2+ + 2e' -» *r 

-2.99 

2H + + 2e — H 2 

0.00 

Ca 2+ + 2e' —♦ Ca 

-2.04 

kqCKs) + — * Ag(s? + Cl" 

0.22 

Ma* + e“ —♦ Na 

-2.7 1 

Cu 2+ + 2e' — Cu 

0.34 

Mq 2+ + 2e' Mq 

-2.30 

0 2 + 2H 2 0 + 4e — 40H' 

0.40 

Be 2t + 2e‘ — Be 

-1.0* 

Cu + + e" —* £u 

0,52 

Al ?+ + Be' —♦ Al 

-1.CC 

I 2 + 2e' —♦ 21- 

0.54 

Ti 2 * + te — Ti 

-1.63 

Fe ?+ + c- ^ Fe 2 ’ 

0.77 

Wn 2+ f 2e" —> Mn 

-1.19 

Hq 2 * + 2e — Hq 

0.90 

Zn 2+ + 2e' Zn 

-0.76 

Ag + + —> Aq 

0.90 

&a 3+ 4* ?c —*• £a 

-052 

Ir ,+ + 3e' — Ir 

1.00 

Fe 2+ + 2c' —* Fe 

-0.44 

Br 2 fl) + 2@" — . 2Br" 

1.07 

Cd 2+ +■ W — Cd 

-0.40 

0 2 + 4H + + 4e — 2H 2 0 

1.23 

Pb*0/s) + 2<f — PKs) + *0/’ 

-0.3 5 

Pb0 2 (s) + *0/-+ 4H + + 2e' — 


Tl + + Tl 

-0.34 

Pb*0 4 (s) + 2H 2 0 

U9 

Co 2 * + 2 g- _ Co 

-0.27 

F 2 (q)+2e' —♦ 2F' 

2.97 


IF TWO HALF-REACTION* ARE COUPLEP TO MAKE A 
WHOLE REACTION, THE HALF-REACTION HI&HER ON 
THE TABLE RUN* RI6HT TO LEFT, A* AN OXIPATION, 
ANP THE LOWER HALF-REACTION I* THE REPUCTION. 
THE WHOLE REACTION’* VOLTAGE I* 

AE° = E°(lower) - E°(higher) 

® 





217 






Example: Lead-Acid Battery. 

IN THE BATTERY UNPER 
yOUR CAR'S HOOP, THE 
ANOPE 1$ METALLIC LEAP, 

P b(0), OXIPATION NUM¬ 
BER 0. THE CATHOPE 1$ 

PbC+IV;, IN THE FORM OF 
Pb0 2 . THE ELECTROPES 
ARE IMMERSEP IN STRON6 
Ufk) SULFURIC ACIP, H 2 S0„ 

THE OXIPATION ANP 
REPUCTION CHAN&E BOTH 
ANOPE ANP CATHOPE 

into PN>n). 

THE HALF REACTION $ ARE 
OX: Pb< 5 ) + tO/Xaq) — PbSO/s) + 2e £° REP = -0.35 V 

REP: Pb0 2 (s? + SO/taq) + 4H + (aq) + 2e — PbSO/s) + 2H 2 0 £° Rep = 1.69 V 
THE OVERALL REACTION APPS UP TO 

PbCs) + PbO/s) + 2$0/(aq) + 4H + Caq) — 2PbS0/s) + 2H 2 0(D 
AE - 1.69 0 . 35 ) = 2.04 V 

CAR BATTERIES USUALLY PUT SIX OF THESE CELLS TOGETHER TO ACHIEVE A TOTAL 
V0LTA6E OF 12V. 


LEAP SULFATE IS INSOLUBLE ANP BUILPS UP ON THE ELECTROPES WHILE SULFURIC 
ACIP ANP THE ELECTROPES ARE CONSUMER VOLTA6E PROPS... 

BUT WHEN THE OR IS 
RUNNIN6, THE ENGINE’S 
MOTION IS CONVER- 
TEP TO ELECTRICAL 
ENERGY BY THE 
ALTERNATOR. THIS 
PUSHES ELECTRONS 
BACK TOWARP THE 
BATTERY’S ANOPE, ANP 
THE REACTIONS ARE 
REVERSEP. THE BAT¬ 
TERY RE£HAR6ES/ 




210 



Example: Fuel Cell 

A FUEL CELL EXTRACTS ELECTRICAL ENERGy FROM A COMBUSTION REACTION SUCH AS 

+ 0, 


2H 2 0 


ONE KINP OF 
FUEL CELL 
INTROPUCES 
HYPR06-EN ANP 
OXyGEN ON 
OPPOSITE 
SIPES OF A 
POLyMER 
(PLASTIC) 
MEMBRANE- 
PROTONS CAN 
PASS THROUGH 
THE MEMBRANE, 
BUT IT BLOCKS 
ELECTRONS. 


*/r 


CATHOPE 


e ANOPE 







F 

IT 

1 

■£51 

ll 


k 

H + 

\ o- m 


t 


awii 


V 






0i 



■= 

izxsili 



IS 


m 



M 


J. 

k 




MEMBRANE 

THE HALF-REACTIONS ARE 
REP: 0 2 + 4H + + Ae —» 2H 2 0 
OX: LL 2LT + 2c’ 


“EXHAUST” 
WATER 


g^ 1.2? v 
g°= o 


r « 


SO THE TOTAL VOLTAGE OF THE CELL IS—OR 

SHOULP BE- 1.29 VOLTS. 


IN REAL LIFE, A CELL GENERATES LESS 
THAN 0,9 V. WHy THE PlFFERENCE? ONE 
REASON IS THAT THE CELL IS NOT 
1 00% EFFICIENT. SOME GASES ESCAPE 
WITHOUT REACTING, ANP THE SySTEM 
SUFFERS FROM ELECTRICAL RESISTANCE. 
ANP A FULL 0.2V IS LOST IN OVER¬ 
COMING THE REACTION’S ACTIVATION 
ENER&y BARRIER. 


J 


W THE WAy-lF HyPROSEN FUEL 
MUST BE EXTRACTED FROM WATER 
IN THE FIRST PLACE, HOW CAN 
you POSSIBLy GAIN MORE 
ENERGy BURNING IT THAN YOU 
USE UP MAKING IT? 


GOOP 

QUES¬ 

TION- 


219 















Voltage and Free Energy 


aw WE PREPICT THE CHAN6E IW VOLTAGE 
WHEW PRESSURES OR CONCENTRATIONS 
ARE WOT STANPARP? THE ANSWER TURNS 
OUT TO BE yES, BECAUSE VOLTA6-E 1$ 
nothing BUT £100$ FREE ENER£y 
IW PIS&UISE. 



OW P. 213, V0LTA6E WAS PERNEP AS ENER6Y PROP PER CHAR6E, 50 TO FlMP 
THE EWER&y CHANGE OF A REACTION, WE MULTIPLy VOLTAGE BV THE AMOUNT 
OF CHAR6E TRANSFERREP-- 


energy = voltage x charge 


SPEClFiaLLy, IF OWE VOLT MOVES ONE 
MOLE OF ELECTRONS, THE TOTAL ENER&y 
PROP TURNS OUT TO BE 96,405 JOULES.* 

1 VOLT-MOL e' ® 96,405 J 



THIS CONVERSION FACTOR, 
96.405 kJ/(VOLT-MOL e), 15 
CALLEP FARAPAV* CON¬ 
STANT, ANP WRITTEN W. IF 
A V0LTA6E OF AE MOVES n 
MOLES OF ELECTRONS, THEN 

ENER6y PROP * n^AE 

THIS REPRESENTS THE MAXI¬ 
MUM AMOUNT OF WORK THE 
CELL CAN POTENTIALLy PO. 



‘OBVIOUSLY, THE PERSON WHO PEFlNEP THE VOLT PJPN’T CONSULT WITH ANY CHEMISTS, WHO WOULP 
PROBABLY PREFER TO MEASURE AE IN UNITS OF 1/96,VOLT, OR “JOLTS” ANP 6ET RIP OF 3. 


210 




NOW THE MAXIMUM WORK A 
REACTION £an po i* -A6, 
WHERE LG 1$ IT* FREE ENER*y. ANP 
A VOLTAIC ££LL I* REALLy A REPOX 
REACTION/ IN OTHER WORP*. 


LG = -n SAG JOULE*, OR 



THE MINU* *!*N I* AN ARTIFACT OF 
OUR PEFINITION*. VOLTAGE I* THE 
*|ZE OF THE ENER&y PROP, WHILE 
LG I* THE ENER*y £HAN*E. *0 
AE > 0 WHEN LG < <?. THAT I*, A 

REPOX REACTION 1$ SPON¬ 
TANEOUS WHEN AE > O. 



$\JM 

RlMf 

%ai 9 

NW 



221 



IN THE LAST CHAPTER, WE SAW HOW 
AS CHANSES WITH SHANSI NS 
CONCENTRATIONS. IF WE HAVE A 
REACTION 

aA + bB ^ cC + dP 
THEN 

LG = AS* + RTlnQ 

WHERE Q IS THE REACTION QUOTIENT 

_ [C] c [P] d 
" [A] B [P] b 

SINCE AE = -LG/nS AT ANy 
CONCENTRATION, WE FlNP 

AE = AE*-(RT/r\£)hQ 

THIS IS CALLEP THE NERNST 
EQUATION, since balance? half¬ 
reaction POTENTIALS ARE REALLy 
WHOLE REACTION POTENTIALS 
MEASURE? ASAINST A HyPROSEN 
ELECTROPE, THE EQUATION IS ALSO 
TRUE OF REPUCTION POTENTIALS S R£p . 

^ = ^ £p -(RT/^>l,Q 

AT EQUILIBRIUM, RECALL, LG * O, 

SO AE = O AS WELL. THAT IS, WHEN 
Q = K eq , THE BATTERy SOES PEAP. 









THERE ARE MANY 
APPLICATIONS OF THE 
NERNST EQUATION. 
WE’LL LOOK AT ONLY 
ONE, WHEN pH = 7. CAT 
STANPARP CONPITIONS, 
REMEMBER, pH = 0 !) pH 
7 IS WHAT WE FINP IN 
LIVING ORGANISMS... 



FOR SIMPLICITY’S SAKE, ASSUME H + APPEARS AS A 
REA6TANT IN THE HALF REACTION CNOT a 
propuct;, anp assume all other species are at 

STANPARP 1M CONCENTRATIONS OR CLOSE TO IT. IN 
THAT CASE WE WRITE THE APJUSTEP VOLTAGE AS £“'• 

E°'= G° ~CRT/n§?lnQ 

IF THE REACTION IS 

hH + + aA + bB 4- ... —* cC + dP + ... 

ANP [A]=[B]=[C]=[P]*1. THEN AW FACTOR* 
ARE EQUAL TO ONE in THE reaction 

QUOTIENT, EXCEPT THE CONCENTRATION OF H + / 


SO 


* E* 7 - CRT/nef)lnC10 7h ) 

* E* 7 - C7hRT/n#) In CIO) 
BUT In CIO) = 2.3, SO THIS 

* E°- [C2.?)C7)hRT/n£] 


NOW ASSUME h * n, THAT IS, A MOLE OF HYPRO- 
&EN IS CONSUMER FOR EACH MOLE OF ELECTRONS, 
WHICH FREQUENTLY HAPPENS IN A NEUTRAL ENVIRON¬ 
MENT. THEN PLU6SIN6 IN ALL THE CONSTANTS &IVES 
THIS SIMPLE EQUATION; 

E*’ * E* - 0.41 VOLTS///// 


NOW WE CAN ] 
TALK ABOUT 
THE VOLTA6-ES \ | 

WITHIN OUR 
OWN BOPIES/ 








Glucose Oxidized 


THE *U6AR 6LU£0$E, C 6 U n 0 6t 1$ THE Zte\C GjjU 

FIJCI OF I lFC AMD A *CV IMAPCDICMT OF K\ JVl 

&< « 

%Kt 


FUEL OF LIFE A KIP A KEY IN6-REPIENT OF 
CELLS. IT 0X1PIZES BY THIS EQUATION: 


C*H 12 0 6 + 60 2 — 4C0 2 + 6H 2 0 

THE HALF-REACTIONS ARE: 

0 2 + 4H + + 4c' — 2H 2 0 

6C0 2 + 24H + + 24c" ^ C 6 U n 0 6 + 4H 2 0 

(WRITTEN AS A REPUCTION AS ALWAYS/) 








THE HALF-REACTIONS BOTH HAVE EQUAL 
AMOUNTS OF H + ANP C, SO WE CAN USE 
THE FORMULA: 

E 0 ' * £*-0.41 

OXY&EN’S REPUCTION REACTION IS IN THE 
TABLE ON P. 217, ANP WE CAN WRITE 

P 7 ' - 1.2? - .41 * 0.02 V 


WE CALCULATE E° OF THE OXlPATION REACTION FROM FREE ENER6Y TABLES. 
SPECIES G% (kJ/MOL) 


£ A H 12 0 A (aq) 

-917.22 

C0 2 

-394.4 

h*o 

-237.10 


A6 P = (-917.22) + (6X-237.10) - (4X-394.4) 
= 24.1 kJ/mol 

E° = -A(SVn£ = -26.1/[(24X94.405)] 

= -0.011 V 

£*' * -0,011 - 0,41 » -0.42 V 



224 




THEN THE VOLTAOE PROP FOR THE 
WHOLE REACTION 15 

££?' = E^'CREP) - E^’COX) 

^ 0.02 - (-0.42) 

* 1.24 VOLT* > o 

THE OXlPATION OF 6LU035E 15 
5PONTANEOU5/' 



,---- 

WHItH RAI5E5 THE QUE5TION; WHY PONT WE ALL JU*T BURST INTO 

FLAMES? THE REA55URIN6 AN5WER 15 THAT 5PONTANEOU5 69MBU5TION 15 
5T0PPEP By THE REA4TION 5 ACTIVATION ENERGY* 



225 









SO FAR THIS CHAPTER, 
WE’VE PESCRIBEP HOW 
TO 6ET ELECTRICITY OUT 
OF A CHEMICAL REACTION... 
BUT WE HAVEN’T PIS- 
CUSSEP HOW TO SET A 
CHEMICAL REACTION 
FROM ELECTRICITY. 

ELErn?oLy$i5 is 

WHAT HAPPENS WHEN A 
SUBSTANCE SPLITS AS 
THE RESULT OF AN 
APPLIEP ELECTRIC 
CURRENT. 

ALUMINUM, FOR EXAMPLE, 
IS EXTRACTEP FROM ITS 
ORE ELECTROLYTICALLY... 



UNFORTUNATELY, WE PON’T HAVE ROOM FOR THE 
PETAILS... ANP SO ELECTROLYSIS WILL HAVE TO BE LEFT 
FOR ANOTHER PAY, ALON£ WITH A FEW OTHER TOPICS 
TO BE PESCRIBEP IN THE FOLLOWING CHAPTER. 


226 




Chapter 12 

Organic Chemistry 

IT’* ALIVE... OR 15 IT? 

OF THE NINETY-TWO NATURALLY OCCURRING ELEMENTS, *OME HAVE 
dOMMANPEP MORE OF OUR ATTENTION THAN OTHER* HYPROCEN, FOR IT* ROLE IN 
AilU5i OXY&EN, FOR IT* REACTIVITY ANP LOVE OF HYPROOEN-, BUT ONLY ONE 
ELEMENT PE5ERVE* IT* VERY OWN BRANCH OF CHEMI5TRY; CARBON. 



227 


-- 

THANKS TO ITS FOUR OUTER ELECTRONS, CARBON ATOMS CAN BON? WITH 
EACH OTHER TO FORM LON& CHAINS, WITH OTHER ATOMS ATTACHE? TO THE 
LEFTOVER ELECTRONS. THE SIMPLEST OF THESE CHAINS ARE THE HYPRO- 
CAR80NS, WHICH CONTAIN NOTHING BUT CARBON AN? HYFR06EN. 



£RUP£ OIL ma?E 
MAINLy OF HyPROCAR- 
BONS. SINCE LON6- 
CHAINS HAVE HIGHER 
BOILIN6 POINTS THAN 
SHORT ONES, OIL 
REFINERIES CAN SEPA¬ 
RATE ^FRACTIONATE”; 
THEM By LENGTH AN? 
THEN CHEMICALLy 
“CRACK” THE LON& 
CHAINS INTO SHORTER 
ONES. GASOLINE IS A 
MIXTURE OF CHAINS 
WITH 5 - 10 CARBONS 
(OCTANE HAS 9). 



229 











HyPROCARBONS LIKE THOSE ON THE PREVIOUS PASE, WITH SINGLE BONPS 
ONLy, ARE (ALLEP AtKANGS* a pouble bonp turns an alkane into an 
alkGNG, anp a triple bonp makes it an aucYNG. inpivipual molecules 

ARE NAMEP ACCORPIN6LY 



BUTENE 





ETHENE 


H 

ETHyNE 


* 



BUTAPIENE (TWO 
ROUBLE BONPS; 







I 

K 


BUTYNE 


w 


BENZENE 



RIN^-SHAPEP STRUCTURES 
HAPPEN T OOI 


r 


TO COMPLICATE MATTERS FURTHER, TWO COMPOUNPS WITH THE SAME CHEMICAL 
FORMULA CAN HAVE PIFFERENT STRUCTURES. VARIANTS OF THE “SAME” MOLECULE 
ARE CALLEP I$OMER$- 


tf- 


H * 

r \ 


u 

( 


w u 


H 


/ 


H 




I 

14 


( 

14 


i 

rt 


H 


/+ 


U 

i 

t 

1+ 




N 

* 


« * 
« i 


U 

t 


/ 




H u 


/ 


u / » / 

t-f-K ^ ” 

v< 


I 


-H 




u 1 ' 

/ 

^ H 

f ORGANIC CHEMISTRV IS FART CHEMISTRY 

V* PART NAME SAME, ANP PART SEOMETRY! 



"TKEV ARE ALSO CALLEP SATURATE? HYPROCARBONS, SINCE THEY HAVE THE MAXIMUM POSSIBLE NUMBER 
OF HYPROSENS. ANYTHING WITH A POUBLE OR TRIPLE BONP IS CALLEP UNSATURATEP. 


THINGS ARE EVEN MORE FUN WHEN OW6EN ANP NITROGEN 6ET INTO THE MIX. 


IF A £HAIN HAS AN OH, IT'S £ALLEP ANP PONT FORGET E5TER5, WHI£H 

AN AUOHOU. SMELL NldE. 



WITH A COOH 6ROUP, ITS A dARBOXyLId 
kCW. (ONLy THE HyPR06-EN dOMES 
OFF, NOT THE WHOLE OH/ 



He 


THIS ONE, ETHyi FORMATE, 
SMELLS LINE RUM... 



NH 2 MANES IT AN AMINE. 



TWO CHAINS LINNEP 9Y OXy&EN FORM 

AN ETHER. 



t t t * I 

U H H tt. H 


ALPEHyPE6 loon line thiSi 



ANP THIS IS A KETONE: 

u n 


ANP PENTyL ACETATE 
IS “BANANA OIL.” 

H O H K I* f ll 

» .1 A * i+ 1 

K ,f k* ft ** ft 




£ARBOHypRATES CHypRATEP £arbon 5 ”) have exmtu twi^e A 5 many 
HYPR 05 EN 5 A 5 OXY 5 EN 5 .* THAT 15 , THEIR 6 EN£Rl£ FORMULA 15 4 ^ 0 )^. THE 
5 IMPLE 5 T EXAMPLES ARE SUSARS, LIKE 6LU60SE, ^W t 2 0 6 . 


H'CL ALPHA-5LU£05E 




HERE ARE THE TWO MAIM 6 LU£ 05 E I 50 MER 5 . IN BETA, THE OH SROUP BE 5 IPE 
0 15 ON THE SAME 5 IPE OF THE RIN 5 A 5 THE 5 IPE £HAIN. IM ALPHA, OH 15 
ON THE OPPOSITE 51 PE FROM THE £HAIN. 


5 IN 6 LE-RINS 

5 U&AR 5 ARE 
£ALLEP 5 IMPLE 
5 U 6 AR 5 OR 
MONOSA^HA- 
RIPES. 5 U£R 05 E, 
THE £ANE 5 U 6 AR 
YOU BUY AT THE 
5 T 0 RE, 15 A 
PISA££HARIPE 
THAT LINK 5 ALPHA- 
5 LU 005 E TO FRU 4 - 
T 05 E, ANOTHER 
5 IMPLE 5 USAR. 


C5L* 




> -a, / 


J 'H 


o;\£l 



o 

; Oh 

» Oh 


I 9’ 

*'%-o «l*-V V> 11 

U /'H \l 1 \ ^o x , * 

or\9* *'" 


H 


t 

Q 


H 



o 


^MERC ARE EXCEPTION*. PEOWRIBOSE f5 £ON5(PEREP A 5U£AR. EVEN TWOU&M JT 15 ONE OX/£EN 
5H0RT. 



LET'S STOP A MOMENT AMP ASK OURSELVES, 


Why Carbon and Only Carbon? 

WHy IS THIS THE ONE ELEMENT THAT FORMS LONS CHAINS? 



SILICON, WHICH 
SITS BENEATH 
CARBON IN THE 
PERIOPIC TABLE, 
ALSO HAS FOUR 
OUTER ELECTRONS, 
BUT WE PON’T 
SEE HYPROSILICON 
CHAINS. 


NOR, FOR THAT MATTER, PO WE SEE 
CHAINS OF OXYSEN OR NITROSEN. 



ONE REASON IS THAT THE C-C BONP IS 
EXCEPTIONALLY STRONG CARBON ATOMS 
ARE SMALL, SO THE SHAREP ELECTRON 
CLOUP IS CLOSE TO THE NUCLEI, WHICH 
ATTRACT IT STRONGLY. 



HERE ARE SOME BONP STRENGTHS OF 
INTEREST. (RECALL THAT THE NUMBERS 
MEAN THE AMOUNT OF ENERGY NEEPEP 
TO BREAK THE BONPj 


BONP 

STRENGTH (kJ/mol) 

t-c 

B47-B56* 

II 

VJ 

611 

VJ 

HI 

0B7 

£-0 

BBS 

£-m 

B5S-4S0* 

Si-Si 

2B0 

Si-0 

BS0 

0-0 

1A6 

0=0 

' 490 

N-N 

IS? 

N=N 

AW 

N=N 

9Ab 


'PEPEMPINS ON V/HAT ELSE IS ATTACHE? TO THE CARBON ATOM. 







~ " ~ 

NOTE THAT THE C-C BONP IS EVEN 
STRONGER THAN THE C-0 BONP. THIS 
MEANS THAT STABLE CARBON CHAINS 
iAN FORM IN THE PRESENCE OF OXYGEN. 



BY CONTRAST, Si-St BONPS ARE MUCH 
WEAKER THAN Si-0 BONPS. OXYSEN 
PISRUPTS $IU£ON CHAINS. MOST SILICON 
ON EARTH EXISTS AS Si0 2 (SANP) OR 
SiO/' IN SILICATE ROCKS. IN FACT, YOU 
OFTEN SEE Oil ANP SANP SI PE BY SIPE- 



ALSO NOTE THAT TWO C-C BONPS ARE 
STRONGER THAN ONE C=C BONP. CAR¬ 
BON PREFERS THIS 



THREE SIN6LE BONPS ARE ALSO STRONGER 
THAN ONE TRIPLE BONP. RESULT- LONS 
CHAINS ARE PREFERREP OVER SHORT ONES. 


BY CONTRAST, OXYSEN PREFERS 0=0 
TO O-O-O, ANP NITROSEN PREFERS TO 
BONP WITH fTSELF AS MsM. RESULT- 
NO OXYSEN OR NITR06EN CHAINSI 



FINALLY, THE C-H BONP IS STRON&. 
HYPROCARBONS ARE STABLE AT ROOM 
TEMPERATURE. OTHER HYPRIPES TENP 
TO BE UNSTABLE AROUNP OXYSEN. 



BONPEP CHAINS, POSSIBLY BRANCHEP 
OR LOOPING BACK ON THEMSELVES AS 
RINSS, WITH A LOT OF HYPR06EN 
ATTACHEP. THIS IS TRUE OF NO 
OTHER ELEMENT. 



BIG, COMPLICATED CARBON MOLECULES FORM THE ESSENTIAL INGREDIENTS 
OF LIFE... IN FACT, CARBON COMPOUNDS ARE SO INTIMIATELY INVOLVED WITH 
LIVING SYSTEMS THAT CHEMISTS REFER TO ALL CARBON COMPOUNDS AS 
OR6AN16 CARBON MAKES LIFE POSSIBLE.' 



LUCKILY FOR CHEMISTS, EVEN THE BIGGEST MOST HORRIBLE ORGANIC 
COMPOUNDS ARE CHAINS OF SIMPLER SUBUNITS ATTACHED END TO END. THE 
SIMPLEST EXAMPLE IS POLYETHLENE PLASTIC, <CH 2 ) n . 


If * H t 

» \ i , 

H tt ^ 



THE INDIVIDUAL UNITS OF THESE CHAINS ARE CALLED 
MONOMERS (“SINGLE TYPES';, AND THE WHOLE CHAIN IS 


polymer. 







POLYPROPYLENE 


234 




NATURE’* POLYMER* ARE A BIT MORE WHIM*I£AL THAN THE*E *IMPLE 
PLA*Tl£*. FOR IN*TAN££, ?OLY$bCC\\Ml\V& COMBINE MANY *U6AR* ENP 
TO ENP. CELLULOSE I* FORMEP of repeatep unit* of beta-6-lU£0*e. 



*TAR£H combine* alph-6-luzo*e monomer*. 

0 * * 

>-0. j*-O v >-o - 

V >-•* s o' / % - • /# "o /#N # - • "o' v 


PE*PITE THE *EEMIN£LY £LO*E *IMILARITY, *TAR£H ANP £ELLULO*E ARE 
VERY PIFFERENT £HEMI£ALLY. THE *TAR£H £HAIN I* MORE EA*ILY BROKEN 
ANP OXIPIZEP A* BOPY FUEL, WHILE THE TOU6-H FIBER* OF £ELLULO*E 
ARE INPI£E*TIBLE TO MO*T ANIMAL*. 




Chemicals of Life 


LIVING- SYSTEMS TEEM WITH NON- 
REPEATING CHAIN*. AMONG THE 
KEY INGREDIENTS ARE AMINO 
A£IP$, SMALL MOLECULES WITH A 
BASIC AMINO GROUP (NH*), AN ACID 
CARBOXYL GROUP (COOW, AND 
SOME OTHER GROUP ALL ATTACHED 
TO THE SAME CARBON ATOM. 


H 

* 1 

>-•- 

,1 ^ _ _ _ 


< 


o 


$TUfF 


o 


FOR SOME REASON, BIOLOGY FAVORS ONLY TWENTY VARIATIONS ON THIS PATTERN. 


/ i 


GLYCINE 


*' ^ 
I 

ALANINE V 




U-A-U J V .. 


W' 1,0 

* ' i M 

• 1 I 

H H H 

LEUCINE 


H-#-K 

\ 

H 

ISOLEUCINE 


n \ , j 


l 

Os. 

SERINE 


»'f I n O-M 

H 14 H 
VALINE 

'Q "'.i 'o. H 

« "-•-o- h h 

i 

W 

THREONINE 




4 « 


PHENYLALANINE 


VA-. °- h 4-;-hY- 








H 

V 0s H 


TYROSINE 


• /I 

V N-# V 

N 

TRYPTOPHAN 1 






v.< u 

* "VA-V 

C 

. ' 

H S 

i 

£Y*TEINE ^•' W 

l 


vi -< 

r 1 N <x 

u~i~n 

rt-4~U 

M-4'W 

I 

N 

*' n M 
LYSINE 


METHIONINE 


«s , 1 -0 

h^'T'V 


0 /7 V 


A$PARTI£ WP 


i.; v„ 

u A*' » H 

H /" H 
H H 


PROLINE 


v 1 ^ 

M-i-H 

I 

M 

»' V. 

H \» ‘ 

AR6ININE 


V_ # ,o ^V*" 0 

' I N 0 *' I O' 


r *o 








l 


HI5TIPINE 


6LUTAMINE 


# * ^ *' \ "C> 

- s .-;* 0 v t- h H 

H' f N Q,. *-•-* 


*-•-« 

A 


■? v o. 


/ V 

# H &LUTAMI£ A£IP 


A5PARA6-INE 



237 



TWO AMINO A£IP$ £AN LINK UP IN A £ONNE£TION <SALLEP THE PEPTIPC BONP. 


<pg?£>' 

0 




PEPTIPE 

BONP 


THE RESULTING SHORT £HAIN STILL HAS NH 4 AT ONE ENP ANP £OOH AT THE OTHER, 
SO MORE AMINO A£IPS £AN JOIN TO MAKE A POl/PEPTlPC iHA/N. 


"Pw * 0 






J? 


0,< 


CHAR6EP OR POLAR 51 PE 
6ROUP5 ATTRACT OR 
REPEL EA£H OTHER... 


V 
4 - 4 * 




V 






% 

«/* 

:<* 


/ 

a. 





THE POLypEPTIPE FOLPS UP, By A PRO- UNTIL IT BECOME* A PROTEIN. ON FA£T, 
£E55 THAT 15 NOT WELL UNPERSTOOP... PROTEINS SOMETIMES HAVE TWO OR MORE 

SEPARATE CHAINS WOUNP TOGETHER.; 




tw 





SOME PROTEINS SERVE AS STRUCTURAL MATERIAL, BUT MOST ARE CATALYSTS FOR 
OTHER REACTIONS- CATALYTIC PROTEINS ARE CALLED ENZYMES. FOR EXAMPLE-- 


WHEN YOU EAT SUGAR, YOUR BOPY MAKES THE ENZYME REC06-NIZES THE PARTICULAR 
ENZyMES THAT BREAK SUGAR POWN- SUGAR MOLECULE- 



ANP CATALyZES THE REACTION THAT THE ENZyME ITSELF IS UNCHANGED IN 

BREAKS IT POWN INTO SMALLER PIECES. THE PROCESS- 



MEANWHILE, ANOTHER PROTEIN CALLEP HEM06L08IN TRANSPORTS OXyGEN THROUGH 
THE BLOOP STREAM TO CELLS, WHERE IT CAN OXlPIZE GLUCOSE ANP FREE THE ENERGY 
YOUR BOPY NEEPS TO KEEP GOING- 



239 




HOW IN THE SAINTEP 
NAME OP GREGOR 
MENPEL POES MY 
BOPy KNOW HOW TO 
PO ANy OF THIS? 



RMA, RIBONUCLEIC ACIP, HAS A LONG SPINE OF 
ALTERNATING PHOSPHATES ANP RIBOSE SUGARS, 
FROM EACH OF WHICH JUTS ONE OF FOUR 
CHEMICAL BASES KNOWN AS A , C, 6, ANP U. 

u 


EACH TRIP¬ 
LET OF BASES, 
OR CODON, SPECI¬ 
FIES A PARTICULAR 
AMINO ACIP. COPING 
SEQUENCES ALWAyS 
BEGIN WITH THE 
COPON AUG, WHICH 
COPES FOR 
METHIONINE. UAG, 
UAA, ANP UGA 
ALL MEAN 
“STOP. 1 ’ 


H. 




V 

VI - 


// 






Apenine 


w 




■K 


t 

\ 

/ 

Uracil 


-M 


K 


«v. 


H- 


Jl 






0, 


C/TOSINE 


K 


‘N 




0 


H-M 

V 4 




s / 
n k 

guanine 



THE WHOLE THING LOOKS 
LIKE A MESSAGE, ANP IT IS! 

(Note that nypROGEN 

ATOMS ARE OMITTEP.; 


THE OTHER NUCLEIC ACIP, PNA* PEOXYRIBO- 
NUCLEIC MV, HAS TWO STRAWS SIMILAR TO 
RNA’S WOUNP AROUNP EACH OTHER. LIKE 
RNA, PNA U*E$ THE BASES A, £, ANP 
but suBSTrruTES T (thymine; FOR U. 



THYMINE 

o N « 

THE TWO STRANPS FIT TOGETHER WITH 
MIRACULOUS PERFECTION: A ALWAYS PAIRS 
WITH T* ANP C ALWAYS PAIRS WITH 6, 
HELP TOGETHER BY HYPRO&EN BONPS. 


H 


if 

*s„ ^ > #~N* 

M -% o* T 


#C H 

VL. r 


■" *v / 

1 ^ "•v V-# 


ji-H >" O 
t 

H 



ONE STRANP OF PNA IS THE COMPLEMENT OF THE OTHER. IN OTHER WORPS, 
PNA CARRIES THE INFORMATION NECESSARY TO REPROPUCE ITSELF/// 
(THE ACTUAL WORK IS PONE BY ENZYMES POWEREP BY REPOX REACTIONS.) 












ANP THERE ARE A LOT OF PETAIL5 IN ORGANIC ANP BIOCHEMISTRY NO ENP TO 
THEM, IN FACT' NOT TO MENTION PHySlCAL, NUCLEAR, ENVIRONMENTAL, NANO-, 
ANP ALL THE OTHER BRANCHES OF CHEMISTRY yES, REAPER, THE TIME HAS 
COME TO REFER yOU TO MORE APVANCEP COURSES, ANP TO CONGRATULATE 
yOU FOR GETTING THROUGH THE BASICS' ’ByE' 



242 




Appendix 

Using Logarithms 


IN SOME OF OUR CHAPTERS, WE USE A 
MATHEMATICAL SHORTHAND CALLEP 
LOGARITHMS COR LOGS, FOR SHORT). 
THE LOGARITHM IS A CONVENIENT, 
COMPACT WAY OF WRITING A NUMBER. 
FOR INSTANCE, INSTEAD OF [H + ] = 10' 7 
WE WRITE pH = 7. pH IS A LOGARITHM. 



A LOGARITHM IS AN EXPONENT. THE COMMON LOGARITHM OF A NUMBER N, 
loq N, IS THE EXPONENT TO WHICH 10 MUST BE RAISE? IN ORPER TO EQUAL N-. 

10“ « N IS THE SAME AS a * log N THAT IS, W io3N = N 

SO log 10 = 1 AN? log 1 * 0 AN? log 100 » 2 CSINCE \O a = 1 , 1 0 z - 100 ). 

AN? log 72.9 = 1.05914 BECAUSE 10 ,S5914 - 72.9 (CHECK IT ON /OUR CALCULATOR.) 



KEy FACT-- WHEN NUMBERS ARE MULTIPLIED, THEIR 
LOGARITHM* ARE ADDED. 

log MN - log M + log N 

THIS IS BECAUSE 10“10 b * 10 Cfl+W . IF M » 10 a AN? 

N = 10 b , THEN MN ^ 10°10 b * 10 (a+b? , SO a+b = log MN. 
BUT a - log M AN? b = log N. 

SIMILARLY 

log(M p ) = pdog M) 

log (”) = -log N 

N 

BECAUSE THIS IS HOW EXPONENTS BEHAVE: 

10' a = — 10 ab = (10 “) b 

10 a 


249 




244 




Index 


absolute entropy, 196-97 
acids and bases, l£5-90 
buffers, 185-89,190 
conjugate pairs, 166,167, 

186 

equivalent weight of, 178 
neutralization, 177—80 
activation energy, 151—54, 
219,225 
air, 4,10, 98 
alchemy, 5—6 
alternator, 218 
amino acids, 236-38,240 
ammonia, 59,163,167,176, 
179 

amu (atomic mass unit), 25, 72 
anions, 20,41,43, 50, 212 
single-atom, 48 
anode, 19,212,213,218 
Aristode, 4—5,11 
atmospheric pressure, 7—8, 
111,142 

atomic mass, 24-26,28 
atomic number, 25-27,40 
atomic size, 39 

atomic weight, 11,12,15,26, 
112 

atoms, 4,13 
atomic theory, 19-44 
atomists, 4,13 
atom building, 34—39 
bonds between, 45—66 
electron affinity, 41—44 
electronegativity, 47, 48,54, 
56, 62, 63 

ionization energy, 40 
net charge, 78 
oxidation number, 79, 210 
See also electrons 
attractions, 106-28 


Avogadro s law, 112 
Avogadro’s number, 72 


balanced equations, 70—73, 
81 

bases. See acids and bases 
battery, 19,213,218,222 
boiling point, 109, 119-21 
carbon chains, 228 
dissolved material, 139 
heating curve, 126—27 
helium, 125 
bomb calorimeter, 96 
bonds, 45—66 
carbon atoms, 228, 232 
potential energy in, 87 
solvation, 131-32 
strength of, 108, 232-33 
See also imermolecular 
forces 

Boyle’s law, 112 
Brand, Hennig, 5 
buffers, 185-89,190 
bystander ion, 180 


calorimetry 96-100 
carbohydrates, 231 
carbon, 14,34,47,82,227, 
232-233 

atom, 21,24,25,228 
hybrid orbital, 60 
oxidants/reductants, 80-81 
phase diagram, 125 
valence electrons bonds, 58 
carbon chains, 228—41 
catalysts, 153-54,239 


catalytic converter, 154 
cathodes, 19,20,212,213 
cations, 20,182,212 
Celsius scale, 88 
Charles’s law, 112 
chemical bonds. See bonds 
chemical reactions, 8-12, 
67-83 

activation energy, 151-54 
alchemy as, 5-6 
catalysts, 1 53—54, 239 
defined, 2 

electricity from, 209—26 
as energy transfer, 89-104 
entropy and, 198-206 
fire as first, 1—3 
ffee energy, 205 
higher-order, 155-57 
hydrolysis, 175 
rate of, 141—64 
redox, 76—77 

reversible, 158—59,195, 207 
solutions and, 129—40 
spontaneous, 201 
collision theory, 146-52 
combination reaction, 69, 
146-52 

combustion, 11,68,69,77, 
219 

heat of, 103 
spontaneous, 225 
compounds, 11—13,79,229 
concentration, 133-34, 
142-43,164,168-69, 

182 

condensation, 118—21 
coolants, 94,95,117 
copper, 3, 93—94 
zinc reaction, 14, 212—13 
corrosion, 6, 77 



covalent bond, 54-58,62-63, 
65 

strength of attraction, 108 
crystalline structures, 48-51 
of carbon, 125 
covalent bonds, 57 
of ice, 123 

ionic bonds, 48—51, 64 
metallic bonds, 51,52—53 
current, electric, 19, 53, 226 


Dalton, John, 13 
decomposition reaction, 69 
Democritus, 4 
dipoles, 106—7 
dissolving process, 129—40 
acids and bases, 168-69, 184 
freezing/boiling points, 
138-39 

salts in water, 129,130, 182 
DNA, 241 

double bond, 56, 58, 61 
double-displacement reaction, 
76 

dynamic balance, 158—59 


elasticity, 110 
electric cells, 211, 212 
electric potential, 213 
electricity, 17-44,209-26 
attractions/repulsions, 90, 
106-28 

metal conductors, 53 
See also negative charge; 
positive charge 
electrochemistry, 209—26 
electrodes, 20,212,218 
electrolysis, 19,20, 226 
electromagnetic radiation, 87 
electronegativity, 47, 48, 54, 
56, 62,63 


electrons, 20,21,24, 26, 28-44 
affinity, 41—44 
bonds, 47, 52,54-58,63, 

232 

dipole attraction, 107 
ionization energy, 40 
metal, 52,53 
orbit, 29-33,36, 60 
outer, 39, 40,56 
paired, 58-59, 61 
particle/wave, 28,,30 
redox reactions, 77-81,103, 
209-19 

rule of eight, 43-44,61 
sharing, 57, 58-59 
shells, 31-39 

electropositivity, 47, 48, 54, 

62 

electrostatic attraction, 48 
elementary reactions, 156,157 
elements, 12-16 
ancient four, 4,10, 11 
atomic number, 25 
carbon's uniqueness, 232—33 
charge extremes, 62 
grouping of, 36-37 
isotopes of, 25 
list of, 27 

oxidation number, 78, 79 
periodic table, 15-16,38-44 
empirical formula, 49,68 
emulsion, 132 
endothermic reactions, 99, 

102,116, 122, 151 
energy, 26,30,31,39, 85-103 
activation, 151—54,225 
collision, 150-51 
conservation law, 86 
electrical, 209-26 
quanta of, 30,194 
spreading out of, 194, 
195-202 

transfer of, 89-104 
enthalpy, 98-99 
change, 131,200,201 


of formation, 100-104,116, 
122,205 

entropy, 195-206 
enzymes, 239 
equilibrium, 118,124, 

158-64,201,222 
acids and bases, 165-90 
equilibrium constant, 160-61, 
175, 182 
pH, 170 

second derivation of, 207-8 
solubility product, 182-84 
weak ionization, 172-73 
equivalent weight, 178 
evaporation, 116-19,122, 
126-28,139 

exothermic reactions, 99,104, 
151 

explosions, 98,99,102-3,114 
explosives, 6,76-77,80-83 


Faraday's constant, 220 
fire, 1-3,4,9,11,67,68 
first-order reaction, 145 
forward reaction, 159,182, 
199,207 

four basic elements, 4,10, 11 
Franklin, Benjamin, 18 
free energy change, 201-6, 
220-23 

free radical, 142 
freezing point, 95,123, 138 
fuel cell, 219 


gases, 6-13, 98,110-14 
characteristics of, 105 
noble, 43-44,107,125 
solubility, 137 
state changes, 116,121, 
124-25 

temperature and, 91,109 


246 



gas laws, 112—14,128 
Gibbs function, 201—5,220 
Gilbert, William, 17 
glucose, 213,224-25,239 
Guericke, Otto von, 7, 111 
gunpowder recipe, 82 


Haber process, 163,200,204 
half-life, 143-44 
half-reactions, 214—19,222, 

224 

halogens, 41 
heat, 86-104 

reaction activation, 151—54 
See also temperature 
heat capacity, 92-97,197 
heat change, 93,96-104,200 
heating curves, 126—28 
heat of combustion, 103 
heat of fusion, 122 
heats of formation, 100—104 
helium, 125 
hemoglobin, 239 
H enderso n-Hasselbalch 
equation, 187—89 
Heraclitus, 4 
Hess’s Law, 101 
Higher-order reactions, 
155-57 

hybrid orbitals, 60 
hydrocarbons, 228—30,233 
hydrogen, 9,12,13,214,227 
atomic number, 26 
carbon chains, 228—31,233 
electron shell, 31, 34, 56 
heat of combustion, 103 
pH, 171 

positive charge, 19, 62 
redox reaction, 214 
hydrogen bond, 55, 64, 94, 
106 

attraction strength, 108,109 
DNA, 241 


hydrolysis, 175 
hydronium, 168 


ice, 123,126-27 
ideal gas, 110,113 
in solution, 130,134,161 
indicator chemicals, 171 
inter molecular forces, 106-9 
internal energy, 90-91 
ion, 20,31,48,49,51,109 
ionic bonds, 48—51, 54, 65 
dipole, 106-8 
polarity, 63 

strength of attraction, 108 
ionic crystals, 48-51 
ionic repulsion, 51,53 
ionization, 31,40 
base constant, 175—76 
equilibrium, 160-64 
high, 43 

ionization energy, 40 
of water, 161,168,170,172, 
185-89,208 
weak, 172—76 
isomers, 229 
isotopes, 25 


Jabir, 5 

Joule,James Prescott, 92 
Joules, 86,92,93,127 


Kelvin scale, 88,110 
kinetic energy, 87, 90-91,150 


lanthanide series, 37 
Lavoisier, Antoine, 10—11 
Lead-acid battery, 218,222 


Le Chateliers principle, 
162-63,184,204 
Lewis diagram, 56,59,61 
life 

chemicals of, 236-41 
glucose oxidation, 224-25 
hydrogen bonding, 64 
origin of, 154 

liquids, 105,106,109,115-21 
boiling point, 119-20 
evaporation/condensation, 
116-21,122 
melting point, 123 
phase diagrams, 125-26 
solubility, 135-37 
solutions, 129-40 
standard molar energy, 197 
surface tension, 115 
suspensions, 132 
See also water 
logarithms, 171,243—44 
London dispersion force, 107 


main-group elements, 37 
mass, 24,28, 72 
mass action, law of, 160 
mass-balance table, 73, 82 
matter, 2-44,105-28 
ancient theories of, 4—5,13 
three types of, 105 
mechanical energy, 87 
melting point, 109,122-23 
heating curve, 126-27 
Mendeleev, Dmitri, 15 
metal ions as acids, 173 
metallic bonds, 52-53,108 
metals, 42,211 
miscibility, 135 
molar heat capacity, 92 
molarity, 134 
mole, 72-73, 81,110, 

112 

Avogadro’s number, 72 


247 



molecules, 13,49, 55—61 
attractions between, 106-9 
charged, 61,63 
collision theory, 146-52 
composition, 57 
ionization fraction, 174 
kinetic energy storage, 194 
shapes, 58-59 
solubility, 136,139 
standard entropy, 197 
weight, 72 
mullite, 69,70 


negative charge, 18-22, 28, 
212 

electron, 20, 24 
negative reduction potential, 
217 

neon, 34,43 

Nernst equation, 222,223 
neutralization, 177-81,190 
neutrons, 24, 25, 26 
noble gases, 43-44,107,125 
non-metals, 42, 47, 56 
nonrepeating chains, 236—38 
nucleic acids, 240—41 
nucleus, 22,25-28,41 


orbitals, 29—36, 43,60 
organic chemistry, 227—42 
oxidants, 80,103 
oxidation, 77,224-25 
oxidation numbers, 78-83, 

210 

oxidation-reduction. See redox 
reactions 

oxygen, 9-14, 47,227, 239 
atomic number, 26 
carbon chains, 230, 231, 

233 

covalent bond, 56,58 


electron shells, 34 
negative charge, 19, 62 
ozone, 142 


partial pressure, 118,119,122, 
137, 146-48 
particles, 20, 24,28,48 
collision of, 146-52 
entropy, 198 
number in mole, 72 
peptide bond, 238 
periodic table, 15-16,38-44 
pH, 170-71,173,176,178-80 
buffers, 185-89 
endpoint, 181 
Nernst equation, 223 
solubility effects, 184 
phase change, 109,119-27,195 
phase diagrams, 124-25 
photons, 87 
picometer, 22 
plasma, 128 
polarity, 62—65, 136 
polyatomic atoms, 50,61, 

78 

polymers, 234—35 
polypeptide chain, 238 
positive charge, 18-22,28,212 
proton, 24 

potential energy; 87,90, 

213 

pottery, 69, 70,73,117 
precipitating, 68 
pressure, 110-12, 124 
constant, 98, 99 
entropy change, 206 
external, 119-20,123 
gas law equation, 113,122 
gas solubility, 137 
ice melting, 123 
Le Chatelier’s principle, 

163, 204 

vapor, 118-22,139 


Priestley, Joseph, 8^-9,11 
properties, 1—16,54 
metals vs. nonmetals, 42 
proteins, 238-39,240 
protons, 24—27 


quantized energy, 30,194 
quantum mechanics, 28, 29, 
61,198 


radiant energy, 86, 87 
rate constant, 144 
Razi, al-, 5 

reactants, 68-69,141-64,202, 
223 

enthalpy of formation, 101, 
116 

mass-balance table, 73 
See also chemical reactions 
reaction constant, 153—54 
reaction equations, 68, 73, 
143—45,207 
reaction products, 68 
reaction quotient, 207 
reaction rate, 141-64 
re ac ti on stoichi o me try, 71 
redox reactions, 76—83, 103, 
209-21 
reductants, 80 
resonance, 61 

reverse reaction, 158-59,195, 
207 

RNA, 240 

rule of eight, 44, 61 


salt, 20,41,48,51 
acid-base neutralization, 
177-80,190 
boiling point, 139 


2 40 



dissociation in liquid, 64, 
129,130,182 

solubility products, 182-83 
saturation, 135,182—84 
second-order reactions, 
146-47,153-55 
soap, 75 

solids, 105,106,109,122-26 
dissolved, 130-32 
standard molar entropy, 197 
solubility, 135—37,184 
products, 182-83 
solutions, 129-40 
acidity measure, 168-76 
buffers, 185-89 
neutralization, 178-80 
pH, 171,178-80 
reaction rate, 142-48 

saturation, 182—84 
titration, 181 
weak acid, 174—76 
solvation, 131—32,138-39 
specific heat, 92,93—95,127 
spontaneous processes, 
192-93,201,204,221, 
225 

starch, 235 

stoichiometric coefficients, 
160 

sublimation, 122,124 
sugars/suerose, 130, 231,239 


superfluid, 125 
surface tension, 115 
suspensions, 132 


temperature, 88—89, 91,104 
boiling point, 120 
calorimetery, 96—97 
critical, 121 
entropy change, 195 
gas law equation, 113 
heat capacity, 92—95 
melting point, 122-25 
reaction rate, 152,164, 
204 

solubility, 135,137 
state effects of, 109 
thermodynamics, 191—208 
second law of, 199 
thermometers, 88,115 
titration, 181 
transition metals, 37,39 
transition state, 149 


valence electrons, 39,40, 56, 
58,79 

vapor pressure, 118-22,139 
vinegar, 130, 174 


voltaic cell, 213 
volts/voltage, 31,213,215-18, 
225 

free energy and, 220-23 
volume, 110,112,113 


water, 12,13,14,19,196 
acids/bases, 168-69,172, 
185-89 

boiling point, 119-20 
dipole molecule, 106 
evaporation, 116-17, 127, 
177 

freezing expansion, 123 
ionization, 161,168, 170, 
172 

ionization constant, 161, 
170,208 

melting point, 123 
molecular shape, 59 
polarity, 62-63, 64 
specific heat, 93, 94, 95, 
127 

splitting, 175 
water constant, 170 
wavelength, 28,29,30 
weights, 11,12,15,72,178 
work energy, 86,98,202, 
221 



About the Authors 


LAKRY 60NICK IS THE SON 
AMP SON-IN-LAW OF CHEMISTS. HE 
ONCE CONSJPEREP A SCIENTIFIC 
CAREER, BUT WISELY ABANPONEP 
THE I PEA AFTER BREAKING TWELVE 
PIECES OF GLASSWARE IN A 
SINGLE, PISTRESSING THREE-HOUR 
CHEMISTRY LAB. HE WRITES ANP 
PRAWS NONFICTION COMIC BOOKS 
ANP IS THE STAFF CARTOONIST 
FOR MU$E MAGAZINE. HE LIVES 
PHYSICALLY IN CALIFORNIA WITH 
HIS FAMILY ANP VIRTUALLY ON THE 
WEB AT www.larryqonick.com. 




CRAI6 CRIPPLE is PROFESSOR OF 
ENVIRONMENTAL ENGINEERING ANP 
SCIENCE AT STANFORP UNIVERSITY, 
WHERE HE TEACHES AQUATIC CHEMI¬ 
STRY ANP ENVIRONMENTAL BIOTECH¬ 
NOLOGY. HE HAS PUBLISHEP MANY 
ARTICLES ON CHEMICALS IN WATER 
ANP WATER CLEANUP, ANP HIS TEAM 
OF GRAP STUPENTS ANP RESEARCH 
ASSOCIATES LIKE TO THINK THEY CAN 
SOLVE THE WORLP’S WATER CRISIS. 
PROF. CRIPPLE ANP HIS WIFE LIVE IN 
CUPERTINO, CALIFORNIA, ALONG WITH 
THEIR POG ANP WHICHEVER OF THEIR 
FOUR KIPS (MOSTLY GROWN) HAPPENS 
TO BE HOME. HIS WEB SITE IS 
www.stanford.edu/ qroup/evpilot/. 
HE BELIEVES THAT BROKEN EQUIP¬ 
MENT IS A NATURAL PART OF SCIENCE. 







If you have ever suspected that "heavy water” is the title of a bootleg Pink Floyd album, 
believed that surface tension is an anxiety disorder, or imagined that a noble gas is 
the result of a heavy meal at Buckingham Palace, then you need The Cartoon Guide to 
Chemistry to set you on the road to chemical literacy. 

You don’t need to be a scientist to grasp these and many other complex ideas, because 
The Cartoon Guide to Chemistry explains them all: the history and basics of chemistry, 
atomic theory, combustion, solubility, reaction stoichiometry, the mole, entropy, and 
much more—all explained in simple, clear, and yes, funny illustrations. Chemistry 
will never be the same! 


Larry Gonick has been creating comics that explain history, science, and other big 
subjects for over thirty years—he wrote his first guide in 1971: Blood from a Stone-. 
A Cartoon Guide to Tax Reform. He has been a Knight Science Journalism Fellow at 
MIT and is currently staff cartoonist for Muse magazine. 

Craig Criddle is a professor of environmental engineering and science at Stanford 
University and has written numerous scientific papers. 



Also Available 


www.larrygonick.com 

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Sign up now for AuthorTracker by visiting 
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Cover illustration by Larry Gonick 


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